Liquid crystal display device

ABSTRACT

The subject is to provide liquid crystal display device having a short response time, a large voltage holding ratio, a low threshold voltage, a large contrast ratio, a long service life and a small flicker rate. 
     The liquid crystal display device having a liquid crystal alignment film formed on the opposing surfaces of a pair of substrates, and a liquid crystal composition therebetween, wherein the liquid crystal alignment film includes a polymer derived from a polyamic acid having a photodegradable group, and the liquid crystal composition includes at least one compound represented by formula (1) as a first component: 
     
       
         
         
             
             
         
       
     
     R 1  is alkyl having 1 to 12 carbons or the like; ring A is 1,4-cyclohexylene, 1,4-phenylene or the like; Z 1  is a single bond or the like; X 1  and X 2  are hydrogen or fluorine; Y 1  is fluorine or the like; and a is 1, 2, 3 or 4.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a 371 of international application of PCTapplication serial no. PCT/JP2015/068745, filed on Jun. 30, 2015, whichclaims the priority benefit of Japan application no. 2014-158464, filedon Aug. 4, 2014. The entirety of each of the abovementioned patentapplications is hereby incorporated by reference herein and made a partof this specification.

TECHNICAL FIELD

The invention relates to a liquid crystal display device, and a liquidcrystal composition having positive dielectric anisotropy and a liquidcrystal alignment film, those of which are used for the device. Itrelates especially to a liquid crystal display device having a mode suchas TN, OCB, IPS, FFS or FPA. It also relates to a liquid crystal displaydevice with a polymer sustained alignment type.

TECHNICAL BACKGROUND

In a liquid crystal display device, a classification based on anoperating mode for liquid crystal molecules includes modes such as PC(phase change), TN (twisted nematic), STN (super twisted nematic), ECB(electrically controlled birefringence), OCB (optically compensatedbend), IPS (in-plane switching), VA (vertical alignment), FFS (fringefield switching) and FPA (field-induced photo-reactive alignment). Aclassification based on a driving mode in the device includes PM(passive matrix) and AM (active matrix). The PM is classified intostatic, multiplex and so forth, and the AM is classified into TFT (thinfilm transistor), MIM (metal-insulator-metal) and so forth. The TFT isfurther classified into amorphous silicon and polycrystal silicon. Thelatter is classified into a high temperature type and a low temperaturetype depending on the production process. A classification based on alight source includes a reflection type utilizing natural light, atransmission type utilizing a backlight and a semi-transmission typeutilizing both natural light and a backlight.

The liquid crystal display device includes a liquid crystal compositionhaving a nematic phase. This composition has suitable characteristics.An AM device having good characteristics can be obtained by animprovement of the characteristics of this composition. Table 1 belowsummarizes the relationship between these two characteristics. Thecharacteristics of the composition will be further explained on thebasis of a commercially available AM device. The temperature range of anematic phase relates to the temperature range in which the device canbe used. A desirable maximum temperature of the nematic phase isapproximately 70° C. or higher and a desirable minimum temperature ofthe nematic phase is approximately −10° C. or lower. The viscosity ofthe composition relates to the response time of the device. A shortresponse time is desirable for displaying moving images on the device.Response time that is one millisecond shorter than that of other devicesis desirable. Thus a small viscosity of the composition is desirable. Asmall viscosity at a low temperature is more desirable.

TABLE 1 Characteristics of Compositions and AM Devices Characteristicsof No. Compositions Characteristics of AM Devices 1 a wide temperaturerange of a a wide temperature range in which nematic phase the devicecan be used 2 a small viscosity a short response time 3 a suitableoptical anisotropy a large contrast ratio 4 a large positive or negativea low threshold voltage and low dielectric anisotropy power consumption,a large contrast ratio 5 a large specific resistance a large voltageholding ratio and a large contrast ratio 6 a high stability toultraviolet a long service life light and heat 7 a large elasticconstant a large contrast ratio and a short response time

The optical anisotropy of the composition relates to the contrast ratioof the device. A large optical anisotropy or a small optical anisotropy,namely a suitable optical anisotropy, is necessary in accordance withthe mode of the device. The product (Δn×d) of the optical anisotropy(Δn) of the composition and the cell gap (d) of the device is designedso as to maximize the contrast ratio. A suitable value of the productdepends on the type of operating mode. This value is approximately 0.45micrometer for a device having a mode such as TN. This value is in therange of approximately 0.20 micrometer to approximately 0.30 micrometerfor a device having an IPS mode or an FFS mode. In these cases, acomposition having a large optical anisotropy is desirable for a devicehaving a small cell gap. A large dielectric anisotropy of thecomposition contributes to a low threshold voltage, low powerconsumption and a large contrast ratio of the device. A large dielectricanisotropy is thus desirable. The stability of the composition toultraviolet light and heat relates to the service life of the device.The device has a long service life when the stability is high. Thesetypes of characteristics are desirable for an AM device used for aliquid crystal projector, a liquid crystal television and so forth.

A liquid crystal composition including a polymer is used for a liquidcrystal display device with a polymer sustained alignment (PSA) type.First, a composition to which a small amount of a polymerizable compoundhas been added is poured into a device. Next, the composition isirradiated with ultraviolet light, while a voltage is applied betweenthe substrates of this device. The polymerizable compound is polymerizedto give a network structure of a polymer in the composition. In thiscomposition, the polymer makes it possible to adjust the orientation ofliquid crystal molecules, and thus the response time of the device isdecreased and image burn-in is improved. Such effects of the polymer canbe expected for a device having a mode such as TN, ECB, OCB, IPS, VA,FFS or FPA.

When a liquid crystal display device is used for a long time, flickersometimes occurs in the display screen. The flicker relates to imageburn-in. It is presumed that the flicker occurs due to the formation ofa potential difference between positive and negative frames when thedevice is driven by AC current. An improvement has been tried in orderto decrease the occurrence of the flicker in view of the structure ofthe device or the components of the composition.

A composition having positive dielectric anisotropy is used for an AMdevice having a TN mode. A composition having negative dielectricanisotropy is used for an AM device having a VA mode. A compositionhaving positive or negative dielectric anisotropy is used for an AMdevice having an IPS mode or an FFS mode. A composition having positiveor negative dielectric anisotropy is used for an AM device with apolymer sustained alignment (PSA) type. An example of a liquid crystalcomposition having positive dielectric anisotropy is disclosed in Patentdocument No. 1 described below.

An adjustment of the orientation of liquid crystal molecules isnecessary for uniform display characteristics in these liquid crystaldisplay devices. That is, specifically, to orient the liquid crystalmolecules on the substrate uniformly in one direction, and to give auniform angle of inclination (pretilt angle) from the substrate plane tothe liquid crystal molecules, for instance. A liquid crystal alignmentfilm plays such a role. The liquid crystal alignment film is one ofimportant elements with regard to display quality of the liquid crystaldisplay device. The role of the liquid crystal alignment film isbecoming important year after year as the quality of the display deviceis improved.

The liquid crystal alignment film is prepared from a liquid crystalaligning agent. A liquid crystal aligning agent used mainly is asolution (varnish) of a polyamic acid or a soluble polyimide dissolvedin an organic solvent. After this solution has been applied to asubstrate, the coating film is heated to give a polyimide-type liquidcrystal alignment film. At present, a rubbing method is industriallyused to give a function for orientation of the liquid crystal moleculesto this alignment film (alignment treatment). The rubbing method is atreatment in which the surface of the liquid crystal alignment film isrubbed in one direction using a cloth planted with fibers such as nylon,rayon and polyester. This method makes it possible to orient liquidcrystal molecules uniformly.

In contrast, a photoalignment method has been proposed in whichalignment treatment is carried out by irradiation of a photo-reactivefilm with light, and this method includes photodegradation,photoisomerization, photodimerization and photobridging (for example,see Non-Patent document No. 1 and Patent documents Nos. 2 to 6). Thephotoalignment method has advantages such that the method gives a highorientation uniformity in comparison with the rubbing method, and thefilm is not injured because of the non-contact alignment method, and thecause that generates a poor display of a liquid crystal display device,such as dusts or static electricity, can be decreased.

Starting materials used for a photoreactive liquid crystal alignmentfilm (hereinafter, sometimes abbreviated to “a photoalignment film”)have been greatly studied. It has been reported that a polyimide, wherea tetracarboxylic acid dianhydride, especially acyclobutanetetracarboxylic acid dianhydride, is used as a startingmaterial, orients liquid crystal molecules uniformly and stably (forexample, see Patent document No. 2). In this method, a film formed on asubstrate is irradiated with ultraviolet light, causing a chemicalchange to the polyimide and thus giving a function for orientation ofthe liquid crystal molecules in one direction. However, a photoalignmentfilm prepared by such a method has a possibility that the voltageholding ratio is decreased because of an increase in impurity ions forinstance, and thus the electrical characteristics are inferior to thoseof an alignment film subjected to rubbing. A molecular structure of thepolyimide has been variously studied to solve this issue (for example,see Patent document Nos. 2 and 3).

The possibility has been pointed out that the photoalignment method hasa smaller anchoring energy than the rubbing method, and is inferior inthe orientation of liquid crystal molecules, and thus the response timeis increased and the image burn-in is caused in a liquid crystal displaydevice. We have found a method as described, for example, in Patentdocument No. 5 that after a polyamic acid has been applied to asubstrate and irradiated with light, it is calcined, giving aphotoalignment film having a large anchoring energy. However, there is apossibility that the light-transmittance is low and the brightness of aliquid crystal display device is decreased, in a photoalignment filmusing a polyamic acid prepared from a diamine having an azo group as astarting material.

PRIOR ART Patent Document

-   -   Patent document No. 1: WO 2010-131594 A.    -   Patent document No. 2: JP 09-297313 A (1997).    -   Patent document No. 3: JP 2004-206091 A.    -   Patent document No. 4: WO 2005-083504 A.    -   Patent document No. 5: JP 2005-275364 A.    -   Patent document No. 6: JP 2006-171304 A.

Non-Patent Document

-   -   Non-Patent document No. 1: EKISHO (in English, liquid crystals)        Vol. 3, No. 4, page 262 (1999).

SUMMARY OF THE INVENTION Subject to be Solved by the Invention

One of the aims of the invention is to provide a liquid crystal displaydevice that has characteristics such as a short response time, a largevoltage holding ratio, a low threshold voltage, a large contrast ratio,a long service life and a small flicker rate. Another aim is to providea liquid crystal composition used for such a device. A further aim is toprovide a liquid crystal composition that satisfies at least one ofcharacteristics such as a high maximum temperature of a nematic phase, alow minimum temperature of a nematic phase, a small viscosity, asuitable optical anisotropy, a large positive dielectric anisotropy, alarge specific resistance, a high stability to ultraviolet light, a highstability to heat and a large elastic constant. An additional aim is toprovide a liquid crystal composition that is suitably balanced betweenat least two of the characteristics.

Means for Solving the Subject

The invention relates to a liquid crystal display device having anelectrode group formed on one or both of a pair of substrates that areopposed to each other, and a plurality of active devices connected tothe electrode group, and a liquid crystal alignment film formed on theopposing surfaces of the pair of substrates, and a liquid crystalcomposition sandwiched in between the pair of substrates, wherein theliquid crystal alignment film includes a polymer derived from a polyamicacid having a photodegradable group, and the liquid crystal compositionincludes at least one compound represented by formula (1) as a firstcomponent, and relates to the liquid crystal composition included in thedevice and the liquid crystal alignment film included in the device:

in formula (1), R¹ is alkyl having 1 to 12 carbons, alkoxy having 1 to12 carbons or alkenyl having 2 to 12 carbons; ring A is1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,2,3-difluoro-1,4-phenylene, 2,6-difluoro-1,4-phenylene,pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl or tetrahydropyran-2,5-diyl;Z¹ is a single bond, ethylene, carbonyloxy or difluoromethyleneoxy; X¹and X² are independently hydrogen or fluorine; Y¹ is fluorine, chlorine,alkyl having 1 to 12 carbons in which at least one hydrogen has beenreplaced by fluorine or chlorine, alkoxy having 1 to 12 carbons in whichat least one hydrogen has been replaced by fluorine or chlorine oralkenyloxy having 2 to 12 carbons in which at least one hydrogen hasbeen replaced by fluorine or chlorine; and a is 1, 2, 3 or 4.

Effect of the Invention

One of the advantages of the invention is to provide a liquid crystaldisplay device that has characteristics such as a short response time, alarge voltage holding ratio, a low threshold voltage, a large contrastratio, a long service life and a small flicker rate. Another advantageis to provide a liquid crystal composition used for such a device. Afurther advantage is to provide a liquid crystal composition thatsatisfies at least one of characteristics such as a high maximumtemperature of a nematic phase, a low minimum temperature of a nematicphase, a small viscosity, a suitable optical anisotropy, a largepositive dielectric anisotropy, a large specific resistance, a highstability to ultraviolet light, a high stability to heat and a largeelastic constant. An additional advantage is to provide a liquid crystalcomposition that is suitably balanced between at least two of thecharacteristics.

EMBODIMENT TO CARRY OUT THE INVENTION

The usage of the terms in this specification and claims is as follows.The terms “liquid crystal composition” and “liquid crystal displaydevice” are sometimes abbreviated to “composition” and “device,”respectively. “Liquid crystal display device” is a generic term for aliquid crystal display panel and a liquid crystal display module.“Liquid crystal compound” is a generic term for a compound having aliquid crystal phase such as a nematic phase or a smectic phase, and fora compound having no liquid crystal phases but being mixed to acomposition for the purpose of adjusting the characteristics, such asthe temperature range of a nematic phase, the viscosity and thedielectric anisotropy. This compound has a six-membered ring such as1,4-cyclohexylene or 1,4-phenylene, and its molecular structure isrod-like. “Polymerizable compound” is a compound that is added to acomposition in order to form a polymer in it. A compound represented byformula (1) is sometimes abbreviated to “compound (1).” At least onecompound selected from the group of compounds represented by formula (1)is sometimes abbreviated to “compound (1).” “Compound (1)” means onecompound, a mixture of two compounds or a mixture of three or morecompounds represented by formula (1). This applies to a compoundrepresented by another formula.

A liquid crystal composition is prepared by mixing a plurality of liquidcrystal compounds. The ratio of a liquid crystal compound (content) isexpressed as a percentage by weight (% by weight) based on the weight ofthe liquid crystal composition. An additive such as an optically activecompound, an antioxidant, an ultraviolet light absorber, a coloringmatter, an antifoaming agent, a polymerizable compound, a polymerizationinitiator and a polymerization inhibitor is added to this liquid crystalcomposition as required. The ratio of the additive (added amount) isexpressed as a percentage by weight (% by weight) based on the weight ofthe liquid crystal composition in the same manner as with the liquidcrystal compound. Weight parts per million (ppm) is sometimes used. Theratio of the polymerization initiator and the polymerization inhibitoris exceptionally expressed on the basis of the weight of thepolymerizable compound.

“A higher limit of the temperature range of a nematic phase” issometimes abbreviated to “the maximum temperature.” “A lower limit ofthe temperature range of a nematic phase” is sometimes abbreviated to“the minimum temperature.” That “a voltage holding ratio is large” meansthat a device has a large voltage holding ratio at a temperature closeto the maximum temperature of a nematic phase as well as at roomtemperature in the initial stages, and that the device has a largevoltage holding ratio at a temperature close to the maximum temperatureof a nematic phase as well as at room temperature, after it has beenused for a long time. The expression “increase the dielectricanisotropy” means that its value is positively increased when thecomposition has positive dielectric anisotropy, and that its value isnegatively increased when the composition has negative dielectricanisotropy.

The expression “at least one ‘A’ may be replaced by ‘B’” means that thenumber of ‘A’ is arbitrary. The position of ‘A’ is arbitrary when thenumber of ‘A’ is one, and the positions can also be selected withoutrestriction when the number of ‘A’ is two or more. The same rule alsoapplies to the expression “at least one ‘A’ has been replaced by ‘B’.”For example, the expression “in the alkyl, at least one —CH₂— may bereplaced by —O— or —S—” includes a group such as —OCH₃, —CH₂OCH₃,—CH₂OCH₂CH₂OCH₃, —SCH₂CH₂CH₃, —CH₂CH₂SCH₃ and —CH₂OCH₂CH₂SCH₃.

The symbol for the terminal group, R¹, is used for a plurality ofcompounds in the chemical formulas of component compounds. In thesecompounds, two groups represented by two arbitrary R¹ may be the same ordifferent. In one case, for example, R¹ of compound (1-1) is ethyl andR¹ of compound (1-2) is ethyl. In another case, R¹ of compound (1-1) isethyl and R¹ of compound (1-2) is propyl. The same rule applies tosymbols such as other terminal groups. In formula (1), two of ring A arepresent when a is 2. In this compound, two groups represented by two ofring A may be the same or different. The same rule applies to twoarbitrary of ring A, when a is greater than 2. The same rule alsoapplies to symbols such as Z² and ring B.

2-Fluoro-1,4-phenylene means the two divalent groups described below.Fluorine may be facing left (L) or facing right (R) in a chemicalformula. The same rule also applies to an asymmetric divalent group suchas tetrahydropyran-2,5-diyl. The same rule also applies to a bondinggroup such as carbonyloxy (—COO— and —OCO—).

A liquid crystal alignment film used for the liquid crystal displaydevice of the invention includes a polymer derived from at least one ofa polyamic acid having a photoreactive group, especially aphotodegradable group and the derivatives of the polyamic acid. That isto say, the liquid crystal alignment film is prepared from a polyamicacid having a photoreactive group or its derivatives. At least one of atetracarboxylic acid dianhydride having a photoreactive group or adiamine having a photoreactive group is an essential component forintroducing the photoreactive group to the polymer. Another component isany other tetracarboxylic acid dianhydride or any other diamine. Anyother tetracarboxylic acid dianhydride includes aliphatictetracarboxylic acid dianhydrides, alicyclic tetracarboxylic aciddianhydrides and aromatic tetracarboxylic acid dianhydrides. Any otherdiamine includes diamines having no side chains, diamines having a sidechain and dihydrazides. The derivative of the polyamic acid includessoluble polyimides, polyamic acid esters, polyhydrazide acids, polyamicacid amides and polyhydrazide acid-amide acids.

Specific examples include the following: (1) polyimides formed by thecyclodehydration of all of amino and carboxyl in a polyamic acid. (2)partial polyimides formed by the partial cyclodehydration of a polyamicacid. (3) polyamic acid esters formed by the transformation of thecarboxyl of a polyamic acid to its ester. (4) polyamic acid-polyamidecopolymers formed by the reaction of a mixture of a tetracarboxylic aciddianhydride and an organic dicarboxylic acid. (5) polyamidoimides formedby the partial or total cyclodehydration of the polyamic acid-polyamidecopolymers. The polyamic acid or its derivatives may be one compound ora mixture of two or more compounds.

A polyamic acid having a photodegradable group or its derivatives isprepared by using a tetracarboxylic acid dianhydride having aphotodegradable group (or a diamine having a photodegradable group) as astarting material. The term “tetracarboxylic acid dianhydride” may meanone compound, or a mixture of two or more tetracarboxylic aciddianhydrides. This rule applies to a diamine.

The invention includes the following items.

Item 1. A liquid crystal display device having an electrode group formedon one or both of a pair of substrates that are opposed to each other,and a plurality of active devices connected to the electrode group, anda liquid crystal alignment film formed on the opposing surfaces of thepair of substrates, and a liquid crystal composition sandwiched inbetween the pair of substrates, wherein the liquid crystal alignmentfilm includes a polymer derived from a polyamic acid having aphotodegradable group, and the liquid crystal composition includes atleast one compound represented by formula (1) as a first component:

in formula (1), R¹ is alkyl having 1 to 12 carbons, alkoxy having 1 to12 carbons or alkenyl having 2 to 12 carbons; ring A is1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,2,3-difluoro-1,4-phenylene, 2,6-difluoro-1,4-phenylene,pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl or tetrahydropyran-2,5-diyl;Z¹ is a single bond, ethylene, carbonyloxy or difluoromethyleneoxy; X¹and X² are independently hydrogen or fluorine; Y¹ is fluorine, chlorine,alkyl having 1 to 12 carbons in which at least one hydrogen has beenreplaced by fluorine or chlorine, alkoxy having 1 to 12 carbons in whichat least one hydrogen has been replaced by fluorine or chlorine oralkenyloxy having 2 to 12 carbons in which at least one hydrogen hasbeen replaced by fluorine or chlorine; and a is 1, 2, 3 or 4.Item 2. The liquid crystal display device according to item 1, whereinthe first component is at least one compound selected from the group ofcompounds represented by formula (1-1) to formula (1-35):

in formula (1-1) to formula (1-35), R¹ is alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons.Item 3. The liquid crystal display device according to item 1 or 2,wherein the ratio of the first component is in the range of 10% byweight to 90% by weight based on the weight of the liquid crystalcomposition.Item 4. The liquid crystal display device according to any one of items1 to 3, wherein the liquid crystal composition includes at least onecompound selected from the group of compounds represented by formula (2)as a second component:

in formula (2), R² and R³ are independently alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons,alkyl having 1 to 12 carbons in which at least one hydrogen has beenreplaced by fluorine or chlorine or alkenyl having 2 to 12 carbons inwhich at least one hydrogen has been replaced by fluorine or chlorine;ring B and ring C are independently 1,4-cyclohexylene, 1,4-phenylene,2-fluoro-1,4-phenylene or 2,5-difluoro-1,4-phenylene; Z² is a singlebond, ethylene or carbonyloxy; and b is 1, 2 or 3.Item 5. The liquid crystal display device according to item 4, whereinthe second component is at least one compound selected from the group ofcompounds represented by formula (2-1) to formula (2-13):

in formula (2-1) to formula (2-13), R² and R³ are independently alkylhaving 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2to 12 carbons, alkyl having 1 to 12 carbons in which at least onehydrogen has been replaced by fluorine or chlorine or alkenyl having 2to 12 carbons in which at least one hydrogen has been replaced byfluorine or chlorine.Item 6. The liquid crystal display device according to item 4 or 5,wherein the ratio of the second component is in the range of 10% byweight to 90% by weight based on the weight of the liquid crystalcomposition.Item 7. The liquid crystal display device according to any one of items1 to 6, wherein the liquid crystal composition includes at least onecompound selected from the group of compounds represented by formula (3)as a third component:

in formula (3), R⁴ and R⁵ are independently alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons,alkenyloxy having 2 to 12 carbons or alkyl having 1 to 12 carbons inwhich at least one hydrogen has been replaced by fluorine or chlorine;ring D and ring F are independently 1,4-cyclohexylene,1,4-cyclohexylene, 1,4-phenylene, 1,4-phenylene in which at least onehydrogen has been replaced by fluorine or chlorine ortetrahydropyran-2,5-diyl; ring E is 2,3-difluoro-1,4-phenylene,2-chloro-3-fluoro-1,4-phenylene, 2,3-difluoro-5-methyl-1,4-phenylene,3,4,5-trifluoronaphthalene-2,6-diyl or 7,8-difluorochroman-2,6-diyl; Z³and Z⁴ are independently a single bond, ethylene, carbonyloxy ormethyleneoxy; c is 1, 2 or 3, d is 0 or 1; and the sum of c and d is 3or less.Item 8. The liquid crystal display device according to item 7, whereinthe third component is at least one compound selected from the group ofcompounds represented by formula (3-1) to formula (3-21):

in formula (3-1) to formula (3-21), R⁴ and R⁵ are independently alkylhaving 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2to 12 carbons, alkenyloxy having 2 to 12 carbons or alkyl having 1 to 12carbons in which at least one hydrogen has been replaced by fluorine orchlorine.Item 9. The liquid crystal display device according to item 7 or 8,wherein the ratio of the third component is in the range of 3% by weightto 30% by weight based on the weight of the liquid crystal composition.Item 10. The liquid crystal display device according to any one of items1 to 9, wherein the liquid crystal alignment film includes a polymerderived from a polyamic acid having at least one photodegradable groupselected from the group of groups represented by formula (XI-1) toformula (XI-16):

in formula (XI-1) to formula (XI-16), R⁶, R⁷, R⁸ and R⁹ areindependently hydrogen, halogen, alkyl having 1 to 6 carbons, alkenylhaving 2 to 6 carbons, alkynyl having 2 to 6 carbons or phenyl; R¹⁰ ishydrogen, alkyl having 1 to 10 carbons or cycloalkyl having 3 to 10carbons; n₁is an integer from 1 to 4; when n₁ is 1, Z⁵ is —SCH₂—, andwhen n₁ is 2, 3 or 4, Z⁵ is a single bond, —SCH₂— or —CH₂S—, with theproviso that at least one of Z⁵ is —SCH₂— or —CH₂S—; and Z⁶ is a groupincluding an aromatic ring.Item 11. The liquid crystal display device according to any one of items1 to 9, wherein the liquid crystal alignment film includes a polymerderived from a compound represented by formula (XI-1-1) to formula(XI-1-5), formula (XI-2-1), formula (XI-3-1), formula (XI-6-1), formula(XI-7-1) or formula (XI-10-1):

Item 12. The liquid crystal display device according to item 10 or 11,wherein the liquidcrystal alignment film includes a polymer derived by further using atleast one compound selected from the group of compounds represented byformula (DI-1) to formula (DI-15):

in formula (DI-1) to formula (DI-7), k is an integer from 1 to 12; G²¹is a single bond, —NH—, —O—, —S—, —S—S—, —SO₂—, —CO—, —CONH—,—CON(CH₃)—, —NHCO—, —C(CH₃)₂—, —C(CF₃)₂—, —(CH₂)_(m)—, —O—(CH₂)_(m)—O—,—N(CH₃)—(CH₂)_(m)—N(CH₃)—, —COO—, —COS— or —S—(CH₂)_(m)—S—; m is aninteger from 1 to 12; n is an integer from 1 to 5; G²² is a single bond,—O—, —S—, —CO—, —C(CH₃)₂—, —C(CF₃)₂— or alkylene having 1 to 10 carbons;at least one hydrogen on the cyclohexane ring or the benzene ring may bereplaced by fluorine, —CH₃, —OH, —CF₃, —CO₂H, —CONH₂ or benzyl, and informula (DI-4), at least one hydrogen on the benzene ring may bereplaced by the following monovalent group represented by formula(DI-4-a) to formula (DI-4-d);

R¹¹ is hydrogen or —CH₃; and a group can be bonded to any one of carbonatoms constituting a ring when the bonding position of the group is notfixed to any one of the carbon atoms, and—NH₂ is bonded to any one of the bonding positions on a cyclohexane ringor a benzene ring excluding the bonding position of G²¹ or G²²; and

in formula (DI-8) to formula (DI-12), R¹² and R¹³ are independentlyalkyl having 1 to 3 carbons or phenyl; G²³ is alkylene having 1 to 6carbons, phenylene or phenylene in which at least one hydrogen has beenreplaced by alkyl; p is an integer from 1 to 10; R¹⁴ is alkyl having 1to 5 carbons, alkoxy having 1 to 5 carbons or chlorine; q is an integerfrom 0 to 3; r is an integer from 0 to 4; R¹⁵ is hydrogen, alkyl having1 to 4 carbons, phenyl or benzyl; G²⁴ is —CH₂— or —NH—; G²⁵ is a singlebond, alkylene having 2 to 6 carbons or 1,4-phenylene; s is 0 or 1; agroup can be bonded to any one of carbon atoms constituting a ring whenthe bonding position of the group is not fixed to any one of the carbonatoms; and —NH₂ is bonded to any one of the bonding positions on abenzene ring; and

in formula (DI-13) to formula (DI-15), G³¹ is a single bond, alkylenehaving 1 to 20 carbons, —CO—, —O—, —S—, —SO₂—, —C(CH₃)₂— or —C(CF₃)₂—;ring K is a cyclohexane ring, a benzene ring or a naphthalene ring, andin these groups at least one hydrogen may be replaced by methyl, ethylor phenyl; and ring L is a cyclohexane ring or a benzene ring, and inthese groups at least one hydrogen may be replaced by methyl, ethyl orphenyl.Item 13. The liquid crystal display device according to item 10 or 11,wherein the liquid crystal alignment film includes a polymer derived byfurther using a compound selected from the group of compoundsrepresented by formula (DI-1-3), formula (DI-4-1), formula (DI-5-1),formula (DI-5-5), formula (DI-5-9), formula (DI-5-12), formula(DI-5-22), formula (DI-5-28), formula (DI-5-30), formula (DI-5-31),formula (DI-7-3), formula (DI-9-1), formula (DI-13-1), formula(DI-13-2), formula (DI-14-1) and formula (DI-14-2):

in formula (DI-1-3), formula (DI-4-1), formula (DI-5-1), formula(DI-5-5), formula (DI-5-9), formula (DI-5-12), formula (DI-5-22),formula (DI-5-28), formula (DI-5-30), formula (DI-5-31), formula(DI-7-3), formula (DI-9-1), formula (DI-13-1), formula (DI-13-2),formula (DI-14-1) and formula (DI-14-2), m is an integer from 1 to 12; nis an integer from 1 to 5; and t is 1 or 2.Item 14. The liquid crystal display device according to any one of items1 to 13, wherein the operating mode of the liquid crystal display deviceis a TN mode, an ECB mode, an OCB mode, an IPS mode, an FFS mode, a PSAmode, or an FPA mode, and the driving mode of the liquid crystal displaydevice is an active matrix mode.Item 15. The liquid crystal display device according to any one of items1 to 14, wherein the operating mode of the liquid crystal display deviceis an IPS mode or an FFS mode, and the driving mode of the liquidcrystal display device is an active matrix mode.Item 16. A liquid crystal composition used for the liquid crystaldisplay device according to any one of items 1 to 9.Item 17. The liquid crystal composition according to item 16, wherein at25° C., the elastic constant (K) is 13 pN or more and the ratio of theelastic constant (K) to the viscosity (η) is 0.8 nN/Pa·s (nm²/s) ormore.Item 18. A liquid crystal display device, wherein the device includesthe liquid crystal composition according to item 17, and the flickerrate at 25° C. is in the range of 0% to 1%.Item 19. A liquid crystal alignment film used for the liquid crystaldisplay device according to any one of items 10 to 13.Item 20. The liquid crystal alignment film according to item 19, whereinthe volume resistivity (p) at 25° C. is 1.0×10¹⁴ Ωcm or more.Item 21. The liquid crystal alignment film according to item 19, whereinthe dielectric constant (c) at 25° C. is in the range of 3 to 5.

The invention further includes the following items. (a) The compositiondescribed above, further including at least one of additives such as anoptically active compound, an antioxidant, an ultraviolet lightabsorber, a coloring matter, an antifoaming agent, a polymerizablecompound, a polymerization initiator and a polymerization inhibitor. (b)The AM device including the composition described above. (c) Thecomposition described above, further including a polymerizable compoundand an AM device with a polymer sustained alignment (PSA) type,including this composition. (d) An AM device with a polymer sustainedalignment (PSA) type, wherein the AM device includes the compositiondescribed above and a polymerizable compound in this composition ispolymerized. (e) A device including the composition described above andhaving a mode of PC, TN, STN, ECB, OCB, IPS, VA, FFS or FPA. (f) Atransmission-type device including the composition described above. (g)Use of the composition described above, as a composition having anematic phase. (h) Use of the composition prepared by the addition of anoptically active compound to the composition described above, as anoptically active composition.

A liquid crystal composition in the liquid crystal display device of theinvention will be explained in the following order. First, theconstitution of component compounds in the composition will beexplained. Second, the main characteristics of the component compoundsand the main effects of these compounds on the composition will beexplained. Third, a combination of the components in the composition, adesirable ratio of the components and its basis will be explained.Fourth, a desirable embodiment of the component compounds will beexplained. Fifth, desirable component compounds will be shown. Sixth,additives that may be added to the composition will be explained.Seventh, methods for synthesizing the component compounds will beexplained. Eighth, the use of the composition will be explained. Theliquid crystal alignment film will be explained in the following order.Ninth, a polyamic acid having a photodegradable group or its derivativeswill be explained. Tenth, any other tetracarboxylic acid dianhydridewill be explained. Eleventh, any other diamine will be explained.Twelfth, a liquid crystal aligning agent will be explained. Thirteenth,a liquid crystal alignment film will be explained.

First, the constitution of component compounds in the composition willbe explained. The compositions of the invention are classified intocomposition A and composition B. Composition A may further include anyother liquid crystal compound, an additive and so forth, in addition toliquid crystal compounds selected from compound (1), compound (2) andcompound (3). “Any other liquid crystal compound” is a liquid crystalcompound that is different from compound (1), compound (2) and compound(3). Such a compound is mixed with the composition for the purpose offurther adjusting the characteristics. The additive includes anoptically active compound, an antioxidant, an ultraviolet lightabsorber, a coloring matter, an antifoaming agent, a polymerizablecompound, a polymerization initiator and a polymerization inhibitor.

Composition B consists essentially of liquid crystal compounds selectedfrom compound (1), compound (2) and compound (3). The term “essentially”means that the composition may include an additive, but does not includeany other liquid crystal compound. Composition B has a smaller number ofcomponents than composition A. Composition B is preferable tocomposition A in view of cost reduction. Composition A is preferable tocomposition B in view of the fact that characteristics can be furtheradjusted by mixing with any other liquid crystal compound.

Second, the main characteristics of the component compounds and the maineffects of these compounds on the characteristics of the compositionwill be explained. The main characteristics of the component compoundsare summarized in Table 2 on the basis of the effects of the invention.In Table 2, the symbol L stands for “large” or “high”, the symbol Mstands for “medium”, and the symbol S stands for “small” or “low.” Thesymbols L, M and S mean a classification based on a qualitativecomparison among the component compounds, and 0 (zero) means that thevalue is close to zero.

TABLE 2 Characteristics of Compounds Compound Compound CompoundCompounds (1) (2) (3) Maximum Temperature S-L S-L S-M Viscosity M-L S-MM Optical Anisotropy M-L M-L M-L Dielectric Anisotropy S-L¹⁾ 0 M-L²⁾Specific Resistance L L L ¹⁾The value of the dielectric anisotropy ispositive. ²⁾The value of the dielectric anisotropy is negative, and thesymbol expresses the magnitude of the absolute value.

The main effects of the component compounds on the characteristics ofthe composition upon mixing the component compounds with the compositionare as follows. Compound (1) increases the dielectric anisotropy.Compound (2) decreases the viscosity or increases the maximumtemperature. Compound (3) increases the permittivity in the minor axisdirection.

Third, a combination of the components in the composition, a desirableratio of the components and its basis will be explained. A desirablecombination of the components in the composition is the first and secondcomponents, the first and third components or the first, second andthird components. A more desirable combination is the first and secondcomponents or the first, second and third components.

A desirable ratio of the first component is approximately 10% by weightor more for increasing the dielectric anisotropy and approximately 90%by weight or less for decreasing the minimum temperature or fordecreasing the viscosity. A more desirable ratio is in the range ofapproximately 15% by weight to approximately 75% by weight. Anespecially desirable ratio is in the range of approximately 20% byweight to approximately 65% by weight.

A desirable ratio of the second component is approximately 10% by weightor more for increasing the maximum temperature or for decreasing theviscosity and approximately 90% by weight or less for increasing thedielectric anisotropy. A more desirable ratio is in the range ofapproximately 20% by weight to approximately 85% by weight. Anespecially desirable ratio is in the range of approximately 30% byweight to approximately 80% by weight.

A desirable ratio of the third component is approximately 3% by weightor more for increasing the dielectric anisotropy and approximately 30%by weight or less for decreasing the minimum temperature. A moredesirable ratio is in the range of approximately 3% by weight toapproximately 25% by weight. An especially desirable ratio is in therange of approximately 5% by weight to approximately 20% by weight.

Fourth, a desirable embodiment of the component compounds will beexplained. In formula (1) to formula (3), R¹ is alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12carbons. Desirable R¹ is alkyl having 1 to 12 carbons for increasing thestability to ultraviolet light or heat. R² and R³ are independentlyalkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenylhaving 2 to 12 carbons, alkyl having 1 to 12 carbons in which at leastone hydrogen has been replaced by fluorine or chlorine or alkenyl having2 to 12 carbons in which at least one hydrogen has been replaced byfluorine or chlorine. Desirable R² or R³ is alkenyl having 2 to 12carbons for decreasing the viscosity and alkyl having 1 to 12 carbonsfor increasing the stability. R⁴ and R⁵ are independently alkyl having 1to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12carbons, alkenyloxy having 2 to 12 carbons or alkyl having 1 to 12carbons in which at least one hydrogen has been replaced by fluorine orchlorine. Desirable R⁴ or R⁵ is alkyl having 1 to 12 carbons forincreasing the stability and alkoxy having 1 to 12 carbons forincreasing the dielectric anisotropy. Alkyl is straight-chain orbranched-chain, and does not include cycloalkyl. Straight-chain alkyl ispreferable to branched-chain alkyl. The same rule applies to a terminalgroup such as alkoxy and alkenyl.

Desirable alkyl is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptylor octyl. More desirable alkyl is ethyl, propyl, butyl, pentyl or heptylfor decreasing the viscosity.

Desirable alkoxy is methoxy, ethoxy, propoxy, butoxy, pentyloxy,hexyloxy or heptyloxy. More desirable alkoxy is methoxy or ethoxy fordecreasing the viscosity.

Desirable alkenyl is vinyl, 1-propenyl, 2-propenyl, 1-butenyl,2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl,1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl or 5-hexenyl. More desirablealkenyl is vinyl, 1-propenyl, 3-butenyl or 3-pentenyl for decreasing theviscosity. A desirable configuration of —CH═CH— in the alkenyl dependson the position of the double bond. Trans is preferable in the alkenylsuch as 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl, 3-pentenyl and3-hexenyl for decreasing the viscosity. Cis is preferable in the alkenylsuch as 2-butenyl, 2-pentenyl and 2-hexenyl.

Desirable alkenyloxy is vinyloxy, allyloxy, 3-butenyloxy, 3-pentenyloxyor 4-pentenyloxy. More desirable alkenyloxy is allyloxy or 3-butenyloxyfor decreasing the viscosity.

Desirable examples of alkyl in which at least one hydrogen has beenreplaced by fluorine or chlorine are fluoromethyl, 2-fluoroethyl,3-fluoropropyl, 4-fluorobutyl, 5-fluoropentyl, 6-fluorohexyl,7-fluoroheptyl or 8-fluorooctyl. More desirable examples are2-fluoroethyl, 3-fluoropropyl, 4-fluorobutyl or 5-fluoropentyl forincreasing the dielectric anisotropy.

Desirable examples of alkenyl in which at least one hydrogen has beenreplaced by fluorine or chlorine are 2,2-difluorovinyl,3,3-difluoro-2-propenyl, 4,4-difluoro-3-butenyl, 5,5-difluoro-4-pentenylor 6,6-difluoro-5-hexenyl. More desirable examples are 2,2-difluorovinylor 4,4-difluoro-3-butenyl for decreasing the viscosity.

Desirable examples of alkenyloxy in which at least one hydrogen has beenreplaced by fluorine or chlorine are 2,2-difluorovinyloxy,3,3-difluoro-2-propenyloxy, 4,4-difluoro-3-butenyloxy,5,5-difluoro-4-pentenyloxy or 6,6-difluoro-5-hexenylosy. More desirableexamples are 2,2-difluorovinyloxy or 4,4-difluoro-3-butenyloxy fordecreasing the viscosity.

Ring A is 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,2,3-difluoro-1,4-phenylene, 2,6-difluoro-1,4-phenylene,pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl or tetrahydropyran-2,5-diyl.Desirable ring A is 1,4-phenylene or 2-fluoro-1,4-phenylene forincreasing the optical anisotropy. Desirable ring B and ring C areindependently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenyleneor 2,5-difluoro-1,4-phenylene. Desirable ring B or ring C is1,4-cyclohexylene for decreasing the viscosity and 1,4-phenylene forincreasing the optical anisotropy. Ring D and ring F are independently1,4-cyclohexylene, 1,4-cyclohexylene, 1,4-phenylene, 1,4-phenylene inwhich at least one hydrogen has been replaced by fluorine or chlorine ortetrahydropyran-2,5-diyl. Desirable ring D or ring F is1,4-cyclohexylene for decreasing the viscosity andtetrahydropyran-2,5-diyl for increasing the dielectric anisotropy, and1,4-phenylene for increasing the optical anisotropy. Ring E is2,3-difluoro-1,4-phenylene, 2-chloro-3-fluoro-1,4-phenylene,2,3-difluoro-5-methyl-1,4-phenylene, 3,4,5-trifluoronaphthalene-2,6-diylor 7,8-difluorochroman-2,6-diyl. Desirable ring E is2,3-difluoro-1,4-phenylene for increasing the dielectric anisotropy.With regard to the configuration of 1,4-cyclohexylene, trans ispreferable to cis for increasing the maximum temperature.Tetrahydropyran-2,5-diyl is

and is preferably

Z¹ is a single bond, ethylene, carbonyloxy or difluoromethyleneoxy.Desirable Z¹ is a single bond for decreasing the viscosity anddifluoromethyleneoxy for increasing the dielectric anisotropy. Z² is asingle bond, ethylene or carbonyloxy. Desirable Z² is a single bond fordecreasing the viscosity. Z³ and Z⁴ are independently a single bond,ethylene, carbonyloxy or methyleneoxy. Desirable Z³ or Z⁴ is a singlebond for decreasing the viscosity and methyleneoxy for increasing thedielectric anisotropy.

X¹ and X² are independently hydrogen or fluorine. Desirable X¹ or X² isfluorine for increasing the dielectric anisotropy.

Y¹ is fluorine, chlorine, alkyl having 1 to 12 carbons in which at leastone hydrogen has been replaced by fluorine or chlorine, alkoxy having 1to 12 carbons in which at least one hydrogen has been replaced byfluorine or chlorine or alkenyloxy having 2 to 12 carbons in which atleast one hydrogen has been replaced by fluorine or chlorine. DesirableY¹ is fluorine for decreasing the minimum temperature.

An example of alkyl in which at least one hydrogen has been replaced byfluorine or chlorine is trifluoromethyl. An example of alkoxyl in whichat least one hydrogen has been replaced by fluorine or chlorine istrifluoromethoxy. An example of alkenyloxy in which at least onehydrogen has been replaced by fluorine or chlorine is trifluorovinyloxy.

a is 1, 2, 3 or 4. Desirable a is 2 for decreasing the minimumtemperature and is 3 for increasing the dielectric anisotropy. b is 1, 2or 3. Desirable b is 1 for decreasing the viscosity and is 2 or 3 forincreasing the maximum temperature. c is 1, 2 or 3, d is 0 or 1, and thesum of c and d is 3 or less. Desirable c is 1 for decreasing theviscosity and is 2 or 3 for increasing the maximum temperature.Desirable d is 0 for decreasing the viscosity and is 1 for decreasingthe minimum temperature.

Fifth, desirable component compounds will be shown. The first componentis compound (1) having a large positive dielectric anisotropy. Desirablecompound (1) is compound (1-1) to compound (1-35) described in item 2.Desirable compounds in view of a decrease in the flicker rate of adevice are as follows. A compound having a single bond ordifluoromethyleneoxy is preferable to a compound having ethylene orcarbonyloxy. A compound having 1,4-phenylene, 2-fluoro-1,4-phenylene,2,3-difluoro-1,4-phenylene, 2,5-difluoro-1,4-phenylene,2,6-difluoro-1,4-phenylene, 2,3,5-trifluoro-1,4-phenylene,pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl, tetrahydropyran-2,5-diyl ornaphthalene-2,6-diyl is preferable to a compound having1,4-cyclohexylene. In these compound, it is desirable that at least oneof the first component should be compound (1-12), compound (1-14),compound (1-15), compound (1-17), compound (1-18), compound (1-23),compound (1-27), compound (1-29) or compound (1-30). It is desirablethat at least two of the first component should be a combination ofcompound (1-12) and compound (1-15), compound (1-14) and compound(1-27), compound (1-18) and compound (1-24), compound (1-18) andcompound (1-29), compound (1-24) and compound (1-29) or compound (1-29)and compound (1-30).

The second component is compound (2) where the dielectric anisotropy isclose to zero. Desirable compound (2) is compound (2-1) to compound(2-13) described in item 5. In these compound, it is desirable that atleast one of the second component should be compound (2-1), compound(2-3), compound (2-5), compound (2-6) or compound (2-7). It is desirablethat at least two of the second component should be a combination ofcompound (2-1) and compound (2-3) or compound (2-1) and compound (2-5).

The third component is compound (3) having a large negative dielectricanisotropy. Desirable compound (3) is compound (3-1) to compound (3-21)described in item 8. In these compounds, it is desirable that at leastone of the third component should be compound (3-1), compound (3-4),compound (3-5), compound (3-7), compound (3-10) or compound (3-15). Itis desirable that at least two of the third component should be acombination of compound (3-1) and compound (3-7), compound (3-1) andcompound (3-15), compound (3-4) and compound (3-7), compound (3-4) andcompound (3-15), compound (3-5) and compound (3-7) or compound (3-5) andcompound (3-10).

Sixth, additives that may be added to the composition will be explained.Such additives include an optically active compound, an antioxidant, anultraviolet light absorber, a coloring matter, an antifoaming agent, apolymerizable compound, a polymerization initiator and a polymerizationinhibitor. The optically active compound is added to the composition forthe purpose of inducing the helical structure of liquid crystalmolecules and giving a twist angle. Examples of such compounds includecompound (4-1) to compound (4-5). A desirable ratio of the opticallyactive compound is approximately 5% by weight or less, and a moredesirable ratio is in the range of approximately 0.01% by weight toapproximately 2% by weight.

The antioxidant is added to the composition in order to maintain a largevoltage holding ratio at a temperature close to the maximum temperatureas well as at room temperature, after the device has been used for along time. A desirable example of the antioxidant is compound (5) wherez is an integer from 1 to 9, for instance.

In compound (5), desirable z is 1, 3, 5, 7 or 9. More desirable z is 7.Compound (5) where z is 7 is effective in maintaining a large voltageholding ratio at a temperature close to the maximum temperature as wellas at room temperature, after the device has been used for a long time,since it has a small volatility. A desirable ratio of the antioxidant isapproximately 50 ppm or more for achieving its effect and isapproximately 600 ppm or less for avoiding a decrease in the maximumtemperature or avoiding an increase in the minimum temperature. A moredesirable ratio is in the range of approximately 100 ppm toapproximately 300 ppm.

Desirable examples of the ultraviolet light absorber includebenzophenone derivatives, benzoate derivatives and triazole derivatives.A light stabilizer such as an amine having steric hindrance is alsodesirable. A desirable ratio of the ultraviolet light absorber or thelight stabilizer is approximately 50 ppm or more for achieving itseffect and is approximately 10,000 ppm or less for avoiding a decreasein the maximum temperature or avoiding an increase in the minimumtemperature. A more desirable ratio is in the range of approximately 100ppm to approximately 10,000 ppm.

A dichroic dye such as an azo dye or an anthraquinone dye is added tothe composition for adjusting to a device having a guest host (GH) mode.A desirable ratio of the coloring matter is in the range ofapproximately 0.01% by weight to approximately 10% by weight. Theantifoaming agent such as dimethyl silicone oil or methyl phenylsilicone oil is added to the composition for preventing foam formation.A desirable ratio of the antifoaming agent is approximately 1 ppm ormore for achieving its effect and is approximately 1,000 ppm or less foravoiding a poor display. A more desirable ratio is in the range ofapproximately 1 ppm to approximately 500 ppm.

The polymerizable compound is added to the composition for adjusting toa device with a PSA (polymer sustained alignment) type. Desirableexamples of the polymerizable compound include compounds such asacrylates, methacrylates, vinyl compounds, vinyloxy compounds, propenylethers, epoxy compounds (oxiranes, oxetanes) and vinyl ketones. Moredesirable examples are acrylate derivatives or methacrylate derivatives.A desirable ratio of the polymerizable compound is approximately 0.05%by weight or more for achieving the effect and approximately 10% byweight or less for preventing display defects. A more desirable ratio isin the range of approximately 0.1% by weight to approximately 2% byweight. A polymerizable compound is polymerized on irradiation withultraviolet light. It may be polymerized in the presence of an initiatorsuch as a photopolymerization initiator. Suitable conditions forpolymerization, and a suitable type and amount of the initiator areknown to a person skilled in the art and are described in theliterature. For example, Irgacure 651 (registered trademark; BASF),Irgacure 184 (registered trademark; BASF) or Darocure 1173 (registeredtrademark; BASF), each of which is a photoinitiator, is suitable forradical polymerization. A desirable ratio of the photopolymerizationinitiator is in the range of approximately 0.1% by weight toapproximately 5% by weight based on the weight of the polymerizablecompound. A more desirable ratio is in the range of approximately 1% byweight to approximately 3% by weight.

The polymerization inhibitor may be added in order to prevent thepolymerization when a polymerizable compound is kept in storage. Thepolymerizable compound is usually added to the composition withoutremoving the polymerization inhibitor. Examples of the polymerizationinhibitor include hydroquinone derivatives such as hydroquinone andmethylhydroquinone, 4-tert-butylcatechol, 4-methoxyphenol andphenothiazine.

Seventh, methods for synthesizing the component compounds will beexplained. These compounds can be synthesized by known methods. Thesynthetic methods will be exemplified as follows. Compound (1-2) andcompound (1-8) are prepared by the method described in JP H02-233626 A(1990). Compound (2-1) is prepared by the method described in JPS59-176221 A (1984). Compound (3-1) and compound (3-7) are prepared bythe method described in JP H02-503441 A (1990). A compound of formula(5) where z is 1 is available from Sigma-Aldrich Corporation. Compound(5) where z is 7, for instance, is synthesized according to the methoddescribed in U.S. Pat. No. 3,660,505.

Compounds whose synthetic methods are not described can be preparedaccording to the methods described in books such as “Organic Syntheses”(John Wiley & Sons, Inc.), “Organic Reactions” (John Wiley & Sons,Inc.), “Comprehensive Organic Synthesis” (Pergamon Press), and“Shin-Jikken Kagaku Kouza” (New experimental Chemistry Course, inEnglish; Maruzen Co., Ltd., Japan). The composition is preparedaccording to known methods using the compounds thus obtained. Forexample, the component compounds are mixed and dissolved in each otherby heating.

Eighth, the use of the composition will be explained. This compositionmainly has a minimum temperature of approximately −10° C. or lower, amaximum temperature of approximately 70° C. or higher, and an opticalanisotropy in the range of approximately 0.07 to approximately 0.20. Acomposition having an optical anisotropy in the range of approximately0.08 to approximately 0.25 may be prepared by adjusting the ratio of thecomponent compounds or by mixing with any other liquid crystal compound.A composition having an optical anisotropy in the range of approximately0.10 to approximately 0.30 may be prepared by this method. A deviceincluding this composition has a large voltage holding ratio. Thiscomposition is suitable for an AM device. This composition is suitableespecially for an AM device having a transmission type. The compositioncan be used as a composition having a nematic phase and as an opticallyactive composition by adding an optically active compound.

The composition can be used for an AM device. It can also be used for aPM device. The composition can also be used for the AM or PM devicehaving a mode such as PC, TN, STN, ECB, OCB, TS, FFS, VA or FPA. It isespecially desirable to use the composition for the AM device having amode of TN, OCB, IPS or FFS. In the AM device having the IPS or FFSmode, the orientation of liquid crystal molecules may be parallel orperpendicular to a glass substrate, when no voltage is applied. Thesedevices may be of a reflection type, a transmission type or asemi-transmission type. It is desirable to use the composition for adevice having the transmission type. The composition can be used for anamorphous silicon-TFT device or a polycrystal silicon-TFT device. Thecomposition is also usable for an NCAP (nematic curvilinear alignedphase) device prepared by microcapsulating the composition, and for a PD(polymer dispersed) device in which a three-dimensional network-polymeris formed in the composition.

Ninth, a polyamic acid having a photodegradable group or its derivativeswill be explained. A desirable liquid crystal alignment film is preparedfrom a liquid crystal aligning agent including a polymer having aphotodegradable group. The polymer is prepared from a polyamic acidformed by the reaction of a tetracarboxylic acid dianhydride having aphotodegradable group with a diamine. The polymer is also prepared froma polyamic acid formed by the reaction of a tetracarboxylic aciddianhydride with a diamine having a photodegradable group. Thederivative of the polyamic acid includes soluble polyimides, polyamicacid esters, polyhydrazide acids, polyamic acid amides and polyhydrazideacid-amide acids. A polymer having a photodegradable group can also beprepared from the derivative of the polyamic acid in the same manner. Aliquid crystal alignment film prepared from such a polymer hasanisotropy. The anisotropy is caused by the anisotropic degradation of amolecular chain by the action of polarized ultraviolet light (seeparagraph 0008 of WO 2014-054785 A). The photodegradable group makes itpossible to cause such degradation.

A Polyamic acid, polyimide and polyamic acid ester, having aphotodegradable group, can suitably be used for a liquid crystalalignment film included in the liquid crystal display device of theinvention. The polyamic acid is a polymer of the following formula (P-1)where R¹⁶ is hydrogen. The polyimide is a polymer represented by thefollowing formula (P-2). The polyamic acid ester is a polymer of thefollowing formula (P-1) where R¹⁶ is alkyl having 1 to 5 carbons.

In formula (P-1), X³ is a tetravalent organic group, Y² is a divalentorganic group, R¹⁶ is hydrogen or alkyl having 1 to 5 carbons, A¹ and A²are independently hydrogen, alkyl having 1 to 10 carbons, alkenyl having2 to 10 carbons or alkynyl having 2 to 10 carbons, those of which mayhave a substituent. In formula (P-2), X⁴ is a tetravalent organic group,and Y³ is a divalent organic group.

The polyamic acid having a photodegradable group or its derivatives hasat least one photoreactive group selected from the group of groupsrepresented by the following formula (XI-1) to formula (XI-16), forinstance. Such a polyamic acid or its derivatives are prepared by usingat least one tetracarboxylic acid dianhydride having a tetravalent grouprepresented by formula (XI-1) to formula (XI-10) and formula (XI-12) toformula (XI-15) as a starting material. Such a polyamic acid or itsderivatives are also prepared by using a diamine having a grouprepresented by formula (XI-11). A polyamic acid represented by formula(XI-16) or its derivatives are photodegradable.

In formula (XI-1) to formula (XI-16), R⁶, R⁷, R⁸ and R⁹ areindependently hydrogen, halogen, alkyl having 1 to 6 carbons, alkenylhaving 2 to 6 carbons, alkynyl having 2 to 6 carbons or phenyl; R¹⁰ ishydrogen, alkyl having 1 to 10 carbons or cycloalkyl having 3 to 10carbons; n₁ is an integer from 1 to 4; when n₁ is 1, Z⁵ is —SCH₂—, andwhen n₁ is 2, 3 or 4, Z⁶ is a single bond, —SCH₂— or —CH₂S—, with theproviso that at least one of Z⁵ is —SCH₂— or —CH₂S—; and Z⁶ is adivalent group including an aromatic ring.

Examples of the divalent group including an aromatic ring, Z⁶, include agroup represented by the following formula (a), and a group formed bythe combination of this group and at least one group selected from thegroup of —COO—, —NH—, —O— and —S—. An example of the combination is-Ph-COO—, where Ph means phenylene.

In (a), R¹⁷ and R¹⁸ are independently hydrogen, alkyl having 1 to 10carbons or cycloalkyl having 3 to 10 carbons; and n₂ is an integer from0 to 5, and when n₂ is 2 or more, a plurality of R¹⁷ (or R¹⁸) may be thesame or different, and Z⁷ is a divalent group derived by excluding twohydrogens from an aromatic hydrocarbon having 6 to 20 carbons.

Desirable examples of the tetracarboxylic acid dianhydride having aphotodegradable group include compounds represented by the followingformula (XI-1-1) to formula (XI-1-7), formula (XI-2-1), formula(XI-3-1), formula (XI-6-1), formula (XI-7-1), formula (XI-8-1), formula(XI-9-1), formula (XI-10-1), formula (XI-10-2), formula (XI-12-1),formula (XI-13-1), formula (XI-13-2), formula (XI-14-1) and formula(XI-15-1).

More desirable examples of the tetracarboxylic acid dianhydride having aphotodegradable group include compounds represented by the precedingformula (XI-1-1) to formula (XI-1-5), formula (XI-2-1), formula(XI-3-1), formula (XI-6-1), formula (XI-7-1) and formula (XI-10-1).

Examples of a compound having a photodegradable group include thefollowing tetracarboxylic acid dialkyl esters.

Examples of a compound having a photodegradable group include thefollowing tetracarboxylic acid dichlorides.

In formula (b), formula (c), formula (d) and formula (e), R¹⁹ and R²⁰are independently alkyl having 1 to 5 carbons, and m₁ is an integer from1 to 4. Specific examples of R¹⁹ include methyl, ethyl, propyl,isopropyl, butyl, s-butyl, isobutyl, t-butyl and pentyl. Incidentally,R¹⁹ is preferably a group having a small number of carbons and beingeasily eliminated, and more preferably methyl, when a polyamic acidester is prepared from tetracarboxylic acid dialkyl esters (b) and (C),and then it is derived to a polyimide by imidation. Specific examples ofR²⁰ include methyl, ethyl, propyl, isopropyl, butyl, s-butyl, isobutyl,t-butyl and pentyl. Desirable m₁ is 2.

Tenth, any other tetracarboxylic acid dianhydride will be explained.When the polyamic acid or its derivatives are prepared, atetracarboxylic acid dianhydride excluding the tetracarboxylic aciddianhydride having a photodegradable group can further be used, and canbe selected from known tetracarboxylic acid dianhydrides withoutrestriction. Such a tetracarboxylic acid dianhydride may belong to thegroup of aromatic systems (including heteroaromatic ring systems) inwhich —CO—O—CO— is bonded directly to the aromatic ring and aliphaticsystems (including heteroatom ring systems) in which —CO—O—CO— is notbonded directly to the aromatic ring.

Examples of such a tetracarboxylic acid dianhydride includetetracarboxylic acid dianhydrides represented by formulas (AN-I) to(AN-VII) in view of easy availability of starting materials, the ease ofthe polymerization, and electrical characteristics of the film.

In formula (AN-I) to formula (AN-VII), X is a single bond or —CH₂—; G isa single bond, alkylene having 1 to 20 carbons, —CO—, —O—, —S—, —SO₂—,—C(CH₃)₂— or —C(CF₃)₂—; and Y is one selected from the group of thefollowing trivalent groups:

In these groups, at least one hydrogen may be replaced by methyl, ethylor phenyl; ring J is a monocyclic hydrocarbon group having 3 to 10carbons or a polycyclic condensed hydrocarbon group having 6 to 30carbons, and in these groups at least one hydrogen may be replaced bymethyl, ethyl or phenyl, and a bonding line crossing a ring is bonded toany one of carbons constituting the ring, where two bonding lines may bebonded to the same carbon; X¹⁰ is alkylene having 2 to 6 carbons; Me ismethyl; Ph is phenyl; G¹⁰ is —O—, —COO— or —OCO—; and i is 0 or 1.

Further details include tetracarboxylic acid dianhydrides represented bythe following formula (AN-1).

In formula (AN-1), R²¹ is hydrogen or —CH₃. G¹¹ is a single bond,alkylene having 1 to 12 carbons, 1,4-phenylene or 1,4-cyclohexylene. X¹¹is a single bond or —CH₂—. G¹² is any one of the trivalent groupsdescribed below.

When G¹² is CH, hydrogen of CH may be replaced by —CH₃. When G¹² is N,G¹¹ is not a single bond or —CH₂—, and X¹¹ is not a single bond.Examples of a tetracarboxylic acid dianhydride represented by formula(AN-1) include compounds represented by the formulas described below.

In formulas (AN-1-2) and (AN-1-14), u is an integer from 1 to 12.

In formula (AN-2), G¹³ is a single bond, —CH₂—, —CH₂CH₂—, —O—, —S—,—C(CH₃)₂—, —SO₂—, —CO—, —C(CF₃)₂— or a divalent group represented by thefollowing formula (G13-1).

In formula (G13-1), desirable phenylene is 1,4-phenylene or1,3-phenylene.

Ring J¹¹ is a cyclohexane ring or a benzene ring. G¹³ may be bonded toany one of positions in ring J¹¹. Examples of the tetracarboxylic aciddianhydride represented by formula (AN-2) include compounds representedby the following formulas.

In formula (AN-2-17), u is an integer from 1 to 12.

In formula (AN-3), X¹¹ is a single bond or —CH₂—. X¹² is —CH₂—, —CH₂CH₂—or —CH═CH—. v is 2. Examples of the tetracarboxylic acid dianhydriderepresented by formula (AN-3) include compounds represented by thefollowing formulas.

In formula (AN-4), X¹¹ is a single bond or —CH₂—. R²² is hydrogen, —CH₃,—CH₂CH₃ or phenyl, and ring J¹² is a cyclohexane ring or a cyclohexenering. Examples of the tetracarboxylic acid dianhydride represented byformula (AN-4) include compounds represented by the following formulas.

In formula (AN-5), w is 0 or 1. Examples of the tetracarboxylic aciddianhydride represented by formula (AN-5) include compounds representedby the following formulas.

In formula (AN-6), ring J¹¹ is a cyclohexane ring or a benzene ring.Examples of the tetracarboxylic acid dianhydride represented by formula(AN-6) include compounds represented by the following formulas.

In formula (AN-7), ring J¹¹ is a cyclohexane ring or a benzene ring.Examples of the tetracarboxylic acid dianhydride represented by formula(AN-7) include compounds represented by the following formulas.

In formula (AN-8), X¹⁰ is alkylene having 2 to 6 carbons, and Ph isphenyl. Examples of the tetracarboxylic acid dianhydride represented byformula (AN-8) include compounds represented by the following formulas.In the following formula, Ph is phenyl.

In formula (AN-9), two of G¹⁰ are independently —O—, —COO— or —OCO—, andi is 0 or 1. Examples of the tetracarboxylic acid dianhydriderepresented by formula (AN-9) include compounds represented by thefollowing formulas.

In formula (AN-10), x is an integer from 1 to 10. Examples of thetetracarboxylic acid dianhydride represented by formula (AN-10) includecompounds represented by the following formulas.

Examples of a tetracarboxylic acid dianhydride that is not describedabove include the following compounds.

In the acid dianhydrides described above, a compound represented byformula (AN-1-1), (AN-1-13), (AN-2-17), (AN-2-28) or (AN-2-29) isespecially desirable in consideration that an improvement of theorientation in a liquid crystal display device is important.

In the acid dianhydrides described above, a compound represented byformula (AN-1-1), (AN-1-13), (AN-2-28) or (AN-2-29) is especiallydesirable in consideration that an improvement of the transmittance in aliquid crystal display device is important.

In the acid dianhydrides described above, a compound represented byformula (AN-2-5), (AN-2-17), (AN-2-21) or (AN-6-3) is especiallydesirable in consideration that an improvement of the electriccharacteristics in a liquid crystal display device is important.

Eleventh, any other diamine will be explained. In the preparation of thepolyamic acid or its derivatives of the invention, diamines excludingthe diamine having a photodegradable group can further be used, and canbe selected from known diamines without restriction.

The diamine is classified into two types based on its structure. That isto say, a diamine having a group branched from the main chain (namely adiamine having a side chain group) and a diamine having no side chaingroups, when the skeleton connecting two amino groups is regarded as amain chain. This side chain group has an effect of increasing a pretiltangle. The side chain group should be a group having 3 or more carbonsfor achieving its effect. Specific examples include alkyl having 3 ormore carbons, alkoxy having 3 or more carbons, alkoxyalkyl having 3 ormore carbons or a group having a steroid skeleton. In a group having oneor more ring, the group is effective as a side chain group when theterminal ring has any one of alkyl having 1 or more carbons, alkoxyhaving 1 or more carbons and alkoxyalkyl having 2 or more carbons as asubstituent. Hereinafter, a diamine that has such a side chain group issometimes abbreviated to “a diamine having a side chain.” A diamine thatdoes not have such a side chain group is sometimes abbreviated to “adiamine having no side chains.”

The pretilt angle required can be achieved by a suitable selection ofthe diamine having no side chains and the diamine having a side chain.The diamine having no side chains or the diamine having a side chain canbe used in order to improve characteristics such as homeotropicorientation, a voltage holding ratio, image burn-in and orientation. Itis desirable that the diamine having a side chain should be used in anamount such that the characteristics of the invention are not spoiled.

The diamine having no side chains will be explained. A known diaminehaving no side chains includes diamines of formulas (DI-1) to (DI-12) orhydrazides of formulas (DI-13) to (DI-15) described below. The diamineincludes hydrazides herein.

In formula (DI-1) to formula (DI-7), k is an integer from 1 to 12; G²¹is a single bond, —NH—, —O—, —S—, —S—S—, —SO₂—, —CO—, —CONH—,—CON(CH₃)—, —NHCO—, —C(CH₃)₂—C(CF₃)₂—, —(CH₂)_(m)—, —O—(CH₂)_(m)—O—,—N(CH₃)—(CH₂)_(n)—N(CH₃)— or —S—(CH₂)_(m)—S—; m is an integer from 1 to12; n is an integer from 1 to 5; G²² is a single bond, —O—, —S—, —CO—,—C(CH₃)₂—, —C(CF₃)₂— or alkylene having 1 to 10 carbons; and at leastone hydrogen of a cyclohexane ring or a benzene ring may be replaced byfluorine, —CH₃, —OH, —CF₃, —CO₂H, —CONH₂ or benzyl, and in formula(DI-4), at least one hydrogen of the benzene ring may be replaced by anmonovalent group represented by the following formula (DI-4-a) toformula (DI-4-d). A group can be bonded to any one of carbon atomsconstituting a ring when the bonding position of the group is not fixedto any one of the carbon atoms. And —NH₂ is bonded to any one of thebonding positions on a cyclohexane ring or a benzene ring excluding thebonding position of G²¹ or G²².

In formulas (DI-4-a) and (DI-4-b), R¹¹ is hydrogen or —CH₃.

In formula (DI-8) to formula (DI-12), R¹² and R¹³ are independentlyalkyl having 1 to 3 carbons or phenyl; G²³ is alkylene having 1 to 6carbons, phenylene or alkyl substituted-phenylene; p is an integer from1 to 10; R¹⁴ is alkyl having 1 to 5 carbons, alkoxy having 1 to 5carbons or chlorine; q is an integer from 0 to 3; r is an integer from 0to 4; R¹⁵ is hydrogen, alkyl having 1 to 4 carbons, phenyl or benzyl;G²⁴ is —CH₂— or —NH—; G²⁵ is a single bond, alkylene having 2 to 6carbons or 1,4-phenylene; s is 0 or 1; a group can be bonded to any oneof carbon atoms constituting a ring when the bonding position of thegroup is not fixed to any one of the carbon atoms; and —NH₂ is bonded toany one of the bonding positions on a benzene ring.

In formula (DI-13) to formula (DI-15), G³¹ is a single bond, alkylenehaving 1 to 20 carbons, —CO—, —O—, —S—, —SO₂—, —C(CH₃)₂— or —C(CF₃)₂—;ring K is a cyclohexane ring, a benzene ring or a naphthalene ring, andin these groups at least one hydrogen may be replaced by methyl, ethylor phenyl; and ring L is a cyclohexane ring or a benzene ring, and inthese groups at least one hydrogen may be replaced by methyl, ethyl orphenyl.

Specific examples of the diamine having no side chains, of formulas(DI-1) to (DI-15) described above include diamines of formulas (DI-1-1)to (DI-15-6).

Examples of diamines represented by formulas (DI-1) to (DI-3) are shownbelow.

Examples of a diamine represented by formula (DI-4) are shown below.

Examples of a diamine represented by formula (DI-5) are shown below.

In formula (DI-5-1), m is an integer from 1 to 12.

In formula (DI-5-12) and formula (DI-5-13), m is an integer from 1 to12.

In formula (DI-5-16), y is an integer from 1 to 6.

In formula (DI-5-30), n is an integer from 1 to 5.

Examples of a diamine represented by formula (DI-6) are shown below.

Examples of a diamine represented by formula (DI-7) are shown below.

In formulas (DI-7-3) and (DI-7-4), m is an integer from 1 to 12, and tis 1 or 2.

Examples of a diamine represented by formula (DI-8) are shown below.

Examples of a diamine represented by formula (DI-9) are shown below.

Examples of a diamine represented by formula (DI-10) are shown below.

Examples of a diamine represented by formula (DI-11) are shown below.

Examples of a diamine represented by formula (DI-12) are shown below.

Examples of a diamine represented by formula (DI-13) are shown below.

In formula (DI-13-2), t is an integer from 1 to 12.

Examples of a diamine represented by formula (DI-14) are shown below.

Examples of a diamine represented by formula (DI-15) are shown below.

The diamine having a side chain will be explained. The side chain groupof the diamine having a side chain includes groups described below.

First, the side chain group includes alkyl, alkyloxy, alkyloxyalkyl,alkylcarbonyl, alkylcarbonyloxy, alkyloxycarbonyl, alkylaminocarbonyl,alkenyl, alkenyloxy, alkenylcarbonyl, alkenylcarbonyloxy,alkenyloxycarbonyl, alkenylaminocarbonyl, alkynyl, alkynyloxy, alkynylcarbonyl, alkynylcarbonyloxy, alkynyloxycarbonyl oralkynylaminocarbonyl. These groups may be straight-chain orbranched-chain. In these groups, alkyl, alkenyl and alkynyl have 3 ormore carbons, with the proviso that 3 or more carbons in a whole groupmay be sufficient for alkyloxyalkyl.

Next, the side chain group includes a group having a ring structure suchas phenyl, phenylalkyl, phenylalkyloxy, phenyloxy, phenylcarbonyl,phenylcarbonyloxy, phenyloxycarbonyl, phenylaminocarbonyl,phenylcyclohexyloxy, cycloalkyl having 3 or more carbons,cyclohexylalkyl, cyclohexyloxy, cyclohexyloxycarbonyl, cyclohexylphenyl,cyclohexylphenylalkyl, cyclohexylphenyloxy, bis(cyclohexyl)oxy,bis(cyclohexyl)alkyl, bis(cyclohexyl)phenyl, bis(cyclohexyl)phenylalkyl,bis(cyclohexyl)oxycarbonyl, bis(cyclohexyl)phenyloxycarbonyl orcyclohexylbis(phenyl)oxycarbonyl, with the proviso that the terminalring has alkyl having one or more carbons, alkoxy having one or morecarbons or alkoxyalkyl having two or more carbons as a substituent.

The side chain group further includes a ring assembly group that is agroup having two or more benzene rings, a group having two or morecyclohexane rings or a group having two or more of rings including abenzene ring and a cyclohexane ring, where the bonding group isindependently a single bond, —O—, —COO—, —OCO—, —CONH— or alkylenehaving 1 to 3 carbons and the terminal ring has alkyl having 1 or morecarbons, fluorine-substituted alkyl having 1 or more carbons, alkoxyhaving 1 or more carbons or alkoxyalkyl having 2 or more carbons as asubstituent. A group having a steroid skeleton is effective as a sidechain group.

The diamine having a side chain includes compounds represented byformulas (DI-16) to (DI-20) described below.

In formula (DI-16), G²⁶ is a single bond, —O—, —COO—, —OCO—, —CO—,—CONH—, —CH₂O—, —OCH₂—, —CF₂O—, —OCF₂— or —(CH₂)_(A)—, and A is aninteger from 1 to 12. A desirable example of G²⁶ is a single bond, —O—,—COO—, —OCO—, —CH₂O— or alkylene having 1 to 3 carbons. An especiallydesirable example is a single bond, —O—, —COO—, —OCO—, —CH₂O—, —CH₂— or—CH₂CH₂—. R²³ is alkyl having 3 to 30 carbons, phenyl, a group having asteroid skeleton, or a group represented by formula (DI-16-a) describedbelow. In the alkyl, at least one hydrogen may be replaced by fluorine,and at least one —CH₂— may be replaced by —O—, —CH═CH— or —C≡C—. In thephenyl, hydrogen may be replaced by fluorine, —CH₃, —OCH₃, —OCH₂F,—OCHF₂, —OCF₃, alkyl having 3 to 30 carbons or alkoxy having 3 to 30carbons. —NH₂ is bonded to any one of the bonding positions on a benzenering. A desirable bonding position is meta or para. That is to say, itis desirable that two bonding positions should be 3- and 5-positions or2- and 5-positions when the bonding position of group “R²³-G²⁶-” is1-position.

In formula (DI-16-a), G²⁷, G²⁸ and G²⁹ are bonding groups, and these areindependently a single bond or alkylene having 1 to 12 carbons, and inthe alkylene at least one —CH₂— may be replaced by —O—, —COO—, —OCO—,—CONH— or —CH═CH—. Ring B²¹, ring B²², ring B²³ and ring B²⁴ areindependently 1,4-phenylene, 1,4-cyclohexylene, 1,3-dioxane-2,5-diyl,pyrimidine-2,5-diyl, pyridine-2,5-diyl, naphthalene-1,5-diyl,naphthalene-2,7-diyl or anthracene-9,10-diyl. In ring B²¹, ring B²²,ring B²³ and ring B²⁴, at least one hydrogen may be replaced by fluorineor —CH₃. D, E and F are independently an integer from 0 to 2, and thesum of these is 1 to 5. When D, E or F is 2, two bonding groups in eachparentheses may be the same or different, and two rings may be the sameor different. R²⁴ is fluorine, —OH, alkyl having 1 to 30 carbons,fluorine-substituted alkyl having 1 to 30 carbons, alkoxy having 1 to 30carbons, —CN, —OCH₂F, —OCHF₂ or —OCF₃, and in the alkyl having 1 to 30carbons at least one —CH₂— may be replaced by a divalent grouprepresented by the following formula (DI-16-b).

In formula (DI-16-b), R²⁵ and R²⁶ are independently alkyl having 1 to 3carbons, and G is an integer from 1 to 6. Desirable examples of R²⁴ arealkyl having 1 to 30 carbons and alkoxy having 1 to 30 carbons.

In formula (DI-17) and formula (DI-18), G³⁰ is a single bond, —CO— or—CH₂—, R²⁷ is hydrogen or —CH₃, and R²⁸ is hydrogen, alkyl having 1 to20 carbons or alkenyl having 2 to 20 carbons. In formula (DI-18), onehydrogen of the benzene ring may be replaced by alkyl having 1 to 20carbons or phenyl. A group can be bonded to any one of carbon atomsconstituting a ring when the bonding position of the group is not fixedto any one of the carbon atoms. It is desirable that in formula (DI-17),one of two “-phenylene-G³⁰—O—” groups should be bonded to 3-position ofthe steroid nuclei, and the other should be bonded to 6-position of thesteroid nuclei. It is desirable that in formula (DI-18), the bondingpositions of two “-phenylene-G³⁰—O—” groups to the benzene ring shouldbe meta or para to the bonding position of the steroid nuclei. Informula (DI-17) and formula (DI-18), —NH₂ is bonded to any one of thebonding positions on a benzene ring.

In formula (DI-19) and formula (DI-20), G³¹ is independently —O— oralkylene having 1 to 6 carbons, and G³² is a single bond or alkylenehaving 1 to 3 carbons. R²⁹ is hydrogen or alkyl having 1 to 20 carbons,and in the alkyl at least one —CH₂— may be replaced by —O—, —CH═CH— or—C≡C—. R³⁰ is alkyl having 6 to 22 carbons, and R³¹ is hydrogen or alkylhaving 1 to 22 carbons. Ring B²⁵ is 1,4-phenylene or 1,4-cyclohexylene,and H is 0 or 1. —NH₂ is bonded to any one of the bonding positions on abenzene ring. It is desirable that each —NH₂ should be located in ameta-position or a para-position to the bonding position of G³¹.

Specific examples of the diamine having a side chain will be shownbelow. The diamine having a side chain represented by formulas (DI-16)to (DI-20) described above includes compounds represented by formulas(DI-16-1) to (DI-20-3) described below.

Examples of a compound represented by formula (DI-16) are shown below.

In formulas (DI-16-1) to (DI-16-11), R³² is alkyl having 1 to 30 carbonsor alkoxy having 1 to 30 carbons, and preferably alkyl having 5 to 25carbons or alkoxy having 5 to 25 carbons. R³³ is alkyl having 1 to 30carbons or alkoxy having 1 to 30 carbons, and preferably alkyl having 3to 25 carbons or alkoxy having 3 to 25 carbons.

In formulas (DI-16-12) to (DI-16-17), R³⁴ is alkyl having 4 to 30carbons, and preferably alkyl having 6 to 25 carbons. R³⁵ is alkylhaving 6 to 30 carbons, and preferably alkyl having 8 to 25 carbons.

In formulas (DI-16-18) to (DI-16-43), R³⁶ is alkyl having 1 to 20carbons or alkoxy having 1 to 20 carbons, and preferably alkyl having 3to 20 carbons or alkoxy having 3 to 20 carbons. R³⁷ is hydrogen,fluorine, alkyl having 1 to 30 carbons, alkoxy having 1 to 30 carbons,—CN, —OCH₂F, —OCHF₂ or —OCF₃, and preferably alkyl having 3 to 25carbons or alkoxy having 3 to 25 carbons. G³³ is alkylene having 1 to 20carbons. Formulas (DI-16-44) to (DI-16-55) are examples of compoundshaving a steroid skeleton.

Examples of a compound represented by formula (DI-17) are shown below.

Examples of a compound represented by formula (DI-18) are shown below.

Examples of a compound represented by formula (DI-19) are shown below.

In formulas (DI-19-1) to (DI-19-12), R³⁸ is hydrogen or alkyl having 1to 20 carbons, and preferably hydrogen or alkyl having 1 to 10 carbons,and R³⁹ is hydrogen or alkyl having 1 to 12 carbons.

Examples of a compound represented by formula (DI-20) are shown below.

In formulas (DI-20-1) to (DI-20-3), R³⁵ is alkyl having 6 to 30 carbons,and R³⁹ is hydrogen or alkyl having 1 to 12 carbons.

Diamines excluding the photosensitive diamine represented by formula(XI-11) and the diamines represented by formulas (DI-1-1) to (DI-20-3),those of which are described above, can be used as the diamine of theinvention. This kind of diamine includes the diamine having a side chainexcluding the diamines of formulas (DI-16-1) to (DI-20-3).

Examples include compounds represented by the following formulas(DI-21-1) to (DI-21-8).

In formulas (DI-21-1) to (DI-21-8), R⁴⁰ is alkyl having 3 to 30 carbons.

In each diamine, a diamine may be partially replaced by a monoamine whenthe ratio of the monoamine to the diamine is in the range of 40 mole %or less. The progress of the polymerization can be retarded, since sucha replacement causes the termination of polymerization that formspolyamic acids. The application characteristics of the liquid crystalaligning agent can be improved without spoiling the effect of theinvention, since the molecular weight of the resulting polymer (polyamicacid or its derivatives) can be adjusted. The number of the monoaminemay be one or two or more if the effect of the invention is not spoiled.The monoamine includes aniline, 4-hydroxyaniline, cyclohexylamine,butylamine, pentylamine, hexylamine, heptylamine, octylamine,nonylamine, decylamine, undecylamine, dodecylamine, tridecylamine,tetradecylamine, pentadecylamine, hexadecylamine, heptadecylamine,octadecylamine or eicosylamine.

When the polyamic acid or its derivatives are prepared, a monoisocyanatecompound may be added to the starting materials. The terminal of theresulting polyamic acid or its derivatives is modified and theirmolecular weights are adjusted by the addition of the monoisocyanatecompound to the starting materials. The application characteristics ofthe liquid crystal aligning agent can be improved without spoiling theeffect of the invention by use of this terminal-modified type polyamicacid or its derivatives. It is desirable from the view described abovethat the content of the monoisocyanate compound in the startingmaterials should be 1 to 10 mol % based on the total amount of thediamines and the tetracarboxylic acid dianhydride. The monoisocyanatecompound includes phenylisocyanate or naphthylisocyanate.

In specific examples described above, a diamine represented by formula(DI-1-3), (DI-5-1), (DI-5-12), (DI-7-3), (DI-13-2), (DI-14-1) or(DI-14-2) is desirable when further improvement of the orientation ofliquid crystal molecules is important.

In specific examples described above, a diamine represented by formula(DI-1-4), (DI-4-1), (DI-5-1), (DI-5-12), (DI-5-28), (DI-5-30), (DI-9-1),(DI-13-1), (DI-13-2), (DI-14-1) or (DI-14-2) is desirable when furtherimprovement of the reactivity and the photosensitivity is important.

In specific examples described above, a diamine represented by formula(DI-1-3), (DI-1-4), (DI-13-1), (DI-13-2), (DI-14-1) or (DI-14-2) isdesirable when further improvement of the transmittance is important.

In specific examples described above, a diamine represented by formula(DI-4-1), (DI-5-5), (DI-5-9), (DI-5-22), (DI-5-28), (DI-5-30),(DI-5-31), (DI-9-1), (DI-14-1) or (DI-14-2) is desirable when furtherimprovement of the electrical characteristics is important.

Twelfth, a liquid crystal aligning agent will be explained. A polyamicacid used for a liquid crystal aligning agent that is used for thepreparation of an alignment film for use in the invention is formed bythe reaction of an acid dianhydride with a diamine in a solvent. In thissynthetic reaction, no specific conditions are necessary except theselection of starting materials. Conditions for a normal synthesis ofpolyamic acids can be applied without modification. Solvents used willbe described below.

The liquid crystal aligning agent may be so-called a blend-type and mayfurther include a polyamic acid or its derivatives, and may furtherinclude components other than the polyamic acid or its derivatives. Thenumber of other component may be one or two or more.

The liquid crystal aligning agent may further include other polymercomponents such as acrylic acid polymers, acrylate polymers andpolyamidoimides that are the reaction product of tetracarboxylic aciddianhydride, a dicarboxylic acid or its derivatives and a diamine,within the range where the effect of the invention is not spoiled(preferably in an amount of 20% by weight or less of the polyamic acidor its derivatives). Other examples include polysiloxanes, polyesters,polyamides, cellulose derivatives, polyacetals, polystyrenes,poly(polystyrene-phenylmaleimide), poly(meth)acrylates and productsformed by the reaction of a polyfunctional carboxylic acid with apolyfunctional epoxy compound.

The polyamic acid or its derivatives can be prepared by a method similarto that for preparing known polyamic acid or its derivatives that isused for the formation of a polyimide film. It is desirable that thetotal molar amount of the tetracarboxylic acid dianhydrides for theirreaction should be almost the same with the total molar amount ofdiamines (in the range of approximately 0.9 to approximately 1.1 in amolar ratio).

The weight-average molecular weight (Mw) of the polyamic acid or itsderivatives is preferably 10,000 to 500,000, and more preferably 20,000to 200,000 in terms of polystyrene equivalents. The molecular weight ofthe polyamic acid or its derivatives can be measured by means of gelpermeation chromatography (GPC).

The presence of the polyamic acid or its derivatives can be confirmed byanalyzing a solid content that is precipitated by the action of a largeamount of a poor solvent, by IR and NMR. The starting materials used canbe confirmed by decomposing the polyamic acid or its derivatives by theaction of an aqueous solution of a strong alkali such as KOH or NaOH,and by extracting the decomposition products with an organic solvent,and then by analyzing by means of GC, HPLC or GC-MS.

An additive such as alkenyl-substituted nadimide compounds, compoundshaving a radical-polymerizable unsaturated double bond, oxazinecompounds, oxazoline compounds, epoxy compounds and silane couplingagents may be added as requested. Such an additive is described inparagraphs 0120 to 0231 of JP 2013-242526 A.

The liquid crystal aligning agent may further include a solvent in viewof the application properties of the liquid crystal aligning agent andthe adjustment of the concentration of the polyamic acid or itsderivatives. The solvent is usable without any restriction when it candissolve high-molecular components. The solvent includes a solventwidely that is usually used for in the production process ofhigh-molecular components such as polyamic acids and soluble polyimides,or for their application, and can properly be selected according to apurpose. The solvent may be used alone or in combination of two or more.

Other solvents include a solvent suitable for the polyamic acid or itsderivatives and another solvent for the purpose of improving theapplication properties.

None-protic polar organic solvents that are suitable for the polyamicacid or its derivatives include N-methyl-2-pyrrolidone,dimethylimidazolidinone, N-methylcaprolactam, N-methylpropionamide,N,N-dimethylacetamide, dimethylsulfoxide, N,N-dimethylformamide,N,N-diethylformamide, diethylacetamide and lactones such asγ-butyrolactone.

Examples of other solvents for the purpose of improving the applicationproperties and so forth include alkyl lactate,3-methyl-3-methoxybutanol, tetraline, isophorone, ethylene glycolmonoalkyl ethers such as ethylene glycol monobutyl ether, diethyleneglycol monoalkyl ethers such as diethylene glycol monoethyl ether,ethylene glycol monoalkyl- or phenylacetate, triethylene glycolmonoalkyl ether, propylene glycol monoalkyl ethers such as propyleneglycol monomethyl ether and propylene glycol monobutyl ether, dialkylmalonates such as diethyl malonate, dipropylene glycol monoalkyl etherssuch as dipropylene glycol monomethyl ether, and ester compounds ofthese acetates.

An especially desirable solvent among these is N-methyl-2-pyrrolidone,dimethylimidazolidinone, γ-butyrolactone, ethylene glycol monobutylether, diethylene glycol monoethyl ether, propylene glycol monobutylether, propylene glycol monomethyl ether or dipropylene glycolmonomethyl ether.

It is desirable that the concentration of a polyamic acid in the liquidcrystal aligning agent should be 0.1 to 40% by weight. When the aligningagent is applied to a substrate, the polyamic acid included is sometimesrequired to dilute for adjusting a film thickness in advance.

The solid content of the aligning agent is not restricted and an optimumvalue may be selected to adjust for a variety of application methodsdescribed below. Usually, the solid content is preferably 0.1 to 30% byweight, and more preferably 1 to 10% by weight based on the weight ofthe varnish in order to suppress unevenness or pinholes formed duringcoating application.

Thirteenth, a liquid crystal alignment film will be explained. Theliquid crystal alignment film is formed by heating a coating film of aliquid crystal aligning agent. The liquid crystal alignment film can beobtained by a normal method where a liquid crystal alignment film isprepared from a liquid crystal aligning agent. The liquid crystalalignment film can be obtained, for example, via a coating film step forforming a coating film of a liquid crystal aligning agent, and a heatingand drying step, and a heating and calcining step. The film may gainanisotropy by irradiation with light, after the coating film step andthe heating and drying step, or after the heating and calcining step, asrequested.

The coating film can be formed by applying a liquid crystal aligningagent to the substrate of a liquid crystal display device. Examples ofthe substrate include a glass substrate on which an ITO (indium tinoxide) electrode, an IZO (In₂O₃—ZnO) electrode, an IGZO (In—Ga—ZnO₄)electrode, a color filter or the like may be formed. A spinner method, aprinting method, a dipping method, a dropping method, an ink-jet methodand so forth are generally known for applying a liquid crystal aligningagent to the substrate.

A method of heat treatment in an oven or an infrared furnace, a methodof heat treatment on a hot plate, and so forth are known as the heatingand drying step. It is desirable that the heating and drying step shouldbe carried out at a temperature where the evaporation of the solvent ispossible. It is more desirable that the step should be carried out at arelatively lower temperature in comparison with the temperature for theheating and calcining step. Specifically, the heating and drying step ispreferably in the range of 30° C. to 150° C., and more preferably in therange of 50° C. to 120° C.

The heating and calcining step can be carried out under the conditionsrequired for the dehydration and ring closure of the polyamic acid orits derivatives. A method of heat treatment in an oven or an infraredfurnace, a method of heat treatment on a hot plate, and so forth areknown for the calcination of the coating film. In general, the step iscarried out preferably at a temperature such as 100 to 300° C. for 1minute to 3 hours, more preferably 120 to 280° C., and furtherpreferably 150 to 250° C.

The method for forming the liquid crystal alignment film in thephotoalignment method is as follows. After the coating film of theliquid crystal aligning agent has been heated and dried, the coatingfilm gains anisotropy by irradiation with linearly polarized light ornon-polarized light of radiation, and the film can be formed by heatingand calcining the coating film. Or after the coating film has beenheated and dried, and heated and calcined, irradiation with linearlypolarized light or non-polarized light of radiation gives the film. Itis desirable that the irradiating step of radiation should be carriedout before the heating and calcining step.

A procedure in which an alignment film gains the ability for orientationof liquid crystals is as follows. A liquid crystal aligning agent of theinvention is applied to a substrate, which is dried by preheating. Whenthe film is irradiated with linearly polarized ultraviolet light via apolarizing plate, a reactive group in a polymer chain that is roughly ina direction parallel to the polarizing direction is photodegraded.Because of this, components in a direction roughly perpendicular to thepolarizing direction of ultraviolet light become dominant in the polymerchain of the film. The substrate is heated, and dehydration and ringclosure of the polyamic acid are carried out, giving the polyimide film,and then a device is assembled using this substrate. When a liquidcrystal composition is injected to the device, the liquid crystalmolecules are aligned in the direction of the polymer chain.Accordingly, the liquid crystal molecules are oriented in the directionperpendicular to the polarizing direction. The film may be irradiatedwith linearly polarized ultraviolet light before the heating step forpolyimidation or after polyimidation by heating.

Furthermore, the coating film can be irradiated with linearly polarizedlight or non-polarized light of radiation in order to increase theability for orientation of liquid crystals in the liquid crystalalignment film while being heated. The irradiation with radiation may becarried out in the heating and drying step or in the heating andcalcining step of a coating film, or between both of them. Thetemperature in the heating and drying step is preferably in the range of30° C. to 150° C., and more preferably in the range of 50° C. to 120° C.The temperature in the heating and calcining step is preferably in therange of 30° C. to 300° C., and more preferably in the range of 50° C.to 250° C.

For example, ultraviolet light or visible light including light withwavelength of 150 to 800 nm can be used as radiation, and ultravioletlight including light of 300 to 400 nm is desirable. Linearly polarizedlight or non-polarized light can be used. The light is not especiallylimited, if the coating film gains the ability for orientation of liquidcrystals by the action of the light. Linearly polarized light isdesirable when a large orientation force is necessary to liquid crystalmolecules.

The liquid crystal alignment film can exhibit a high ability fororientation of liquid crystals by photo-irradiation with light of lowenergy. The light dose of linearly polarized light in the irradiatingstep of radiation is preferably 0.05 to 20 J/cm², and more preferably0.5 to 10 J/cm². The wavelength of linearly polarized light ispreferably 200 to 400 nm, and more preferably 300 to 400 nm. Theirradiation angle of linearly polarized light to a film surface is notespecially limited. When a large orientation force to liquid crystalmolecules is necessary, it is desirable in view of a decrease inorientation treatment time that the light should be perpendicular to thesurface of the film if possible. The liquid crystal alignment film canorient liquid crystal molecules in the direction perpendicular to thepolarization direction of linearly polarized light by irradiation withlinearly polarized light.

When a pretilt angle is necessary, light irradiated to the film may beof linearly polarized light or non-polarized light as described above.The light dose is preferably 0.05 to 20 J/cm², and especially preferably0.5 to 10 J/cm², and the wavelength is preferably 250 to 400 nm, andespecially preferably 300 to 380 nm. The irradiation angle of light tothe film surface is not especially limited, and 30 to 60 degrees aredesirable in view of a decrease in orientation treatment time.

A light source used in the irradiating step includes anultra-high-pressure mercury lamp, a high-pressure mercury lamp, alow-pressure mercury lamp, a deep UV lamp, a halogen lamp, a metalhalide lamp, a high-power metal halide lamp, a xenon lamp, amercury-xenon lamp, an excimer lamp, a KrF-excimer lasers, a fluorescentlamp, an LED lamp, a sodium lamp and a microwave exciting electrodelesslamp, those of which can be used without limitation.

The film thickness of the liquid crystal alignment film is notespecially limited, and is preferably 10 to 300 nm, and more preferably30 to 150 nm. The film thickness can be measured with known thicknessmeter such as a meter showing the difference in level and anellipsometer.

The alignment film is characterized by an especially large anisotropy oforientation. The magnitude of such anisotropy can be evaluated bypolarized infrared spectroscopy described in JP 2005-275364 A and soforth. The magnitude is also evaluated by ellipsometry that is shown inexamples described below. It is believed that an alignment film having alarger anisotropy of a film has a larger orientation force to a liquidcrystal composition.

The liquid crystal layer, that is the layer of liquid crystalcomposition, is formed in which a liquid crystal composition issandwiched between a pair of substrates where the surfaces of liquidcrystal alignment films are opposed to each other. In the formation ofthe liquid crystal layer, a spacer, such as fine particles and a plasticsheet, can be located between a pair of the substrates to form asuitable distance, as requested.

EXAMPLES

The invention will be explained in more detail by way of examples. Theinvention is not limited to the examples. The invention includes amixture of the composition in Composition Example M1 and the compositionin Composition Example M2. The invention also includes a mixtureprepared by mixing at least two compositions in Composition Examples.The invention includes a polyamic acid prepared from a mixture of twotetracarboxylic acid dianhydrides described in Synthetic Examples 2 and3. The invention includes a polyamic acid prepared from a mixture of atleast two starting materials (a diamine, a tetracarboxylic aciddianhydride or its derivatives) described in Synthetic Examples. Thesame rule applies to examples such as the production of devices.Compounds prepared herein were identified by methods such as NMRanalysis. The characteristics of the compounds, the compositions and thedevices were measured by the methods described below.

NMR Analysis

A model DRX-500 apparatus made by Bruker BioSpin Corporation was usedfor measurement. In the measurement of ¹H-NMR, a sample was dissolved ina deuterated solvent such as CDCl₃, and the measurement was carried outunder the conditions of room temperature, 500 MHz and the accumulationof 16 scans. Tetramethylsilane (TMS) was used as an internal standard.In the measurement of ¹⁹F-NMR, CFCl₃ was used as the internal standard,and 24 scans were accumulated. In the explanation of the nuclearmagnetic resonance spectra, the symbols s, d, t, q, quin, sex, m and brstand for a singlet, a doublet, a triplet, a quartet, a quintet, asextet, a multiplet and line-broadening, respectively.

Gas Chromatographic Analysis

A gas chromatograph Model GC-14B made by Shimadzu Corporation was usedfor measurement. The carrier gas was helium (2 milliliters per minute).The sample injector and the detector (FID) were set to 280° C. and 300°C., respectively. A capillary column DB-1 (length 30 meters, bore 0.32millimeter, film thickness 0.25 micrometer, dimethylpolysiloxane as thestationary phase, non-polar) made by Agilent Technologies, Inc. was usedfor the separation of component compounds. After the column had beenkept at 200° C. for 2 minutes, it was further heated to 280° C. at therate of 5° C. per minute. A sample was dissolved in acetone (0.1% byweight), and 1 microliter of the solution was injected into the sampleinjector. A recorder used was a Model C-R5A Chromatopac Integrator madeby Shimadzu Corporation or its equivalent. The resulting gaschromatogram showed the retention time of peaks and the peak areascorresponding to the component compounds.

Solvents for diluting the sample may also be chloroform, hexane and soforth. The following capillary columns may also be used in order toseparate the component compounds: HP-1 made by Agilent Technologies Inc.(length 30 meters, bore 0.32 millimeter, film thickness 0.25micrometer), Rtx-1 made by Restek Corporation (length 30 meters, bore0.32 millimeter, film thickness 0.25 micrometer), and BP-1 made by SGEInternational Pty. Ltd. (length 30 meters, bore 0.32 millimeter, filmthickness 0.25 micrometer). A capillary column CBP1-M50-025 (length 50meters, bore 0.25 millimeter, film thickness 0.25 micrometer) made byShimadzu Corporation may also be used for the purpose of avoiding anoverlap of peaks of the compounds.

The ratio of the liquid crystal compounds included in the compositionmay be calculated according to the following method. The liquid crystalcompounds (a mixture) are detected by use of a gas chromatograph (FID).The ratio of peak areas in the gas chromatogram corresponds to the ratio(ratio by weight) of the liquid crystal compounds. When the capillarycolumn described above is used, the correction coefficient of respectiveliquid crystal compounds may be regarded as 1 (one). Accordingly, theratio (percentage by weight) of the liquid crystal compounds can becalculated from the ratio of peak areas.

Samples for Measurement

A composition itself was used as a sample when the characteristics ofthe composition or the device were measured. When the characteristics ofa compound were measured, a sample for measurement was prepared bymixing this compound (15% by weight) with mother liquid crystals (85% byweight). The characteristic values of the compound were calculated fromthe values obtained from measurements by an extrapolation method:(Extrapolated value)=(Measured value of sample)−0.85×(Measured value ofmother liquid crystals)/0.15. When a smectic phase (or crystals)deposited at 25° C. at this ratio, the ratio of the compound to themother liquid crystals was changed in the order of (10% by weight: 90%by weight), (5% by weight: 95% by weight) and (1% by weight: 99% byweight). The values of the maximum temperature, the optical anisotropy,the viscosity and the dielectric anisotropy regarding the compound wereobtained by means of this extrapolation method.

The mother liquid crystals described below were used. The ratio of thecomponent compounds were expressed as a percentage by weight.

24%

36%

25%

15%Measurement Methods

The characteristics were measured according to the following methods.Most are methods described in the JEITA standards (JEITA-ED-2521B) whichwas deliberated and established by Japan Electronics and InformationTechnology Industries Association (abbreviated to JEITA), or themodified methods. No thin film transistors (TFT) were attached to a TNdevice used for measurement.

(1) Maximum Temperature of a Nematic Phase (NI; ° C.):

A sample was placed on a hot plate in a melting point apparatus equippedwith a polarizing microscope and was heated at the rate of 1° C. perminute. The temperature was measured when part of the sample began tochange from a nematic phase to an isotropic liquid. A higher limit ofthe temperature range of a nematic phase may be abbreviated to “themaximum temperature.”

(2) Minimum Temperature of a Nematic Phase (Tc; ° C.):

A sample having a nematic phase was placed in glass vials and then keptin freezers at temperatures of 0° C., −10° C., −20° C., −30° C. and −40°C. for 10 days, and then the liquid crystal phases were observed. Forexample, when the sample maintained the nematic phase at −20° C. andchanged to crystals or a smectic phase at −30° C., Tc was expressed as<−20° C. A lower limit of the temperature range of a nematic phase maybe abbreviated to “the minimum temperature.”

(3) Viscosity (Bulk Viscosity; η; Measured at 20° C.; mPa·s):

An E-type viscometer made by Tokyo Keiki Inc. was used for measurement.

(4) Viscosity (rotational viscosity; γ1; measured at 25° C.; mPa·s):

The measurement was carried out according to the method described in M.Imai, et al., Molecular Crystals and Liquid Crystals, Vol. 259, 37(1995). A sample was poured into a TN device in which the twist anglewas 0 degrees and the distance between the two glass substrates (cellgap) was 5 micrometers. A voltage was applied to this device andincreased stepwise with an increment of 0.5 volt in the range of 16 to19.5 volts. After a period of 0.2 second with no voltage, a voltage wasapplied repeatedly under the conditions of a single rectangular wavealone (rectangular pulse; 0.2 second) and of no voltage (2 seconds). Thepeak current and the peak time of the transient current generated by theapplied voltage were measured. The value of rotational viscosity wasobtained from these measured values and the calculating equation (8) onpage 40 of the paper presented by M. Imai, et al. The value ofdielectric anisotropy necessary for this calculation was obtained by useof the device that had been used for the measurement of rotationalviscosity, according to the method that will be described below.

(5) Optical Anisotropy (Refractive Index Anisotropy; an; Measured at 25°C.):

The measurement was carried out using an Abbe refractometer with apolarizing plate attached to the ocular, using light at a wavelength of589 nanometers. The surface of the main prism was rubbed in onedirection, and then a sample was placed on the main prism. Therefractive index (n∥) was measured when the direction of the polarizedlight was parallel to that of rubbing. The refractive index (n⊥) wasmeasured when the direction of polarized light was perpendicular to thatof rubbing. The value of the optical anisotropy (Δn) was calculated fromthe equation: Δn=n=n⊥.

(6) Dielectric Anisotropy (Δ∈; Measured at 25° C.):

A sample was poured into a TN device in which the distance between thetwo glass substrates (cell gap) was 9 micrometers and the twist anglewas 80 degrees. Sine waves (10 V, 1 kHz) were applied to this device,and the dielectric constant (∈∥) in the major axis direction of liquidcrystal molecules was measured after 2 seconds. Sine waves (0.5 V, 1kHz) were applied to this device and the dielectric constant (∈⊥) in theminor axis direction of the liquid crystal molecules was measured after2 seconds. The value of dielectric anisotropy was calculated from theequation: Δ∈=∈∥−∈⊥.

(7) Threshold Voltage (Vth; Measured at 25° C.; V):

An LCD evaluation system Model LCD-5100 made by Otsuka Electronics Co.,Ltd. was used for measurement. The light source was a halogen lamp. Asample was poured into a TN device having a normally white mode, inwhich the distance between the two glass substrates (cell gap) was4.45/Δn (micrometers) and the twist angle was 80 degrees. A voltage tobe applied to this device (32 Hz, rectangular waves) was stepwiseincreased in 0.02 V increments from 0 V up to 10 V. The device wasperpendicularly irradiated with light simultaneously, and the amount oflight passing through the device was measured. A voltage-transmittancecurve was prepared, in which the maximum amount of light corresponded to100% transmittance and the minimum amount of light corresponded to 0%transmittance. The threshold voltage was expressed as voltage at 90%transmittance.

(8) Voltage Holding Ratio (VHR-1; Measured at 25° C.; %):

A TN device used for measurement had a polyimide-alignment film, and thedistance between the two glass substrates (cell gap) was 5 micrometers.A sample was poured into the device, and then this device was sealedwith a UV-curable adhesive. A pulse voltage (60 microseconds at 5 V) wasapplied to this TN device and the device was charged. A decreasingvoltage was measured for 16.7 milliseconds with a high-speed voltmeter,and area A between the voltage curve and the horizontal axis in a unitcycle was obtained. Area B was an area without the decrease. The voltageholding ratio was expressed as a percentage of area A to area B.

(9) Voltage Holding Ratio (VHR-2; Measured at 80° C.; %):

The voltage holding ratio was measured by the method described above,except that it was measured at 80° C. instead of 25° C. The resultingvalues were represented by the symbol VHR-2.

(10) Voltage Holding Ratio (VHR-3; Measured at 25° C.; %):

The stability to ultraviolet light was evaluated by measuring a voltageholding ratio after irradiation with ultraviolet light. A TN device usedfor measurement had a polyimide-alignment film and the cell gap was 5micrometers. A sample was poured into this device, and then the devicewas irradiated with light for 20 minutes. The light source was anultra-high-pressure mercury lamp USH-500D (produced by Ushio, Inc.), andthe distance between the device and the light source was 20 centimeters.In the measurement of VHR-3, a decreasing voltage was measured for 16.7milliseconds. A composition having a large VHR-3 has a high stability toultraviolet light. The value of VHR-3 is preferably 90% or more, andmore preferably 95% or more.

(11) Voltage Holding Ratio (VHR-4; Measured at 25° C.; %):

A TN device into which a sample was poured was heated in aconstant-temperature bath at 80° C. for 500 hours, and then thestability to heat was evaluated by measuring the voltage holding ratio.In the measurement of VHR-4, a decreasing voltage was measured for 16.7milliseconds. A composition having a large VHR-4 has a high stability toheat.

(12) Response Time (τ; measured at 25° C.; millisecond):

An LCD evaluation system Model LCD-5100 made by Otsuka Electronics Co.,Ltd. was used for measurement. The light source was a halogen lamp. Thelow-pass filter was set at 5 kHz. A sample was poured into a FFS deviceassembled in Examples described below. This device was sealed with aUV-curable adhesive. Rectangular waves (60 Hz, 5 V, 0.5 second) wereapplied to this device. The device was perpendicularly irradiated withlight simultaneously, and the amount of light passing through the devicewas measured. The transmittance was regarded as 100% when the amount oflight reached a maximum. The transmittance was regarded as 0% when theamount of light reached a minimum. Rise time (τr; millisecond) was thetime required for a change from 90% to 10% transmittance. Fall time (τf;millisecond) was the time required for a change from 10% to 90%transmittance. The response time was expressed as the sum of the risetime and the fall time thus obtained. The response time is preferably 60ms or less, and more preferably 40 ms or less.

(13) Elastic Constants (K; Measured at 25° C.; pN):

A LCR meter Model HP 4284-A made by Yokokawa Hewlett-Packard, Ltd. wasused for measurement. A sample was poured into a homogeneous device inwhich the distance between the two glass substrates (cell gap) was 20micrometers. An electric charge of 0 volts to 20 volts was applied tothis device, and the electrostatic capacity and the applied voltage weremeasured. The measured values of the electric capacity (C) and theapplied voltage (V) were fitted to equation (2.98) and equation (2.101)on page 75 of “Ekisho Debaisu Handobukku” (Liquid Crystal DeviceHandbook, in English; The Nikkan Kogyo Shimbun, Ltd., Japan) and thevalues of K11 and K33 were obtained from equation (2.99). Next, thevalue of K22 was calculated from equation (3.18) on page 171 of the bookand the values of K11 and K33 thus obtained. The elastic constant K wasexpressed as an average value of K11, K22 and K33.

(14) Specific Resistance (ρ; Measured at 25° C.; Ωcm):

A sample of 1.0 milliliter was poured into a vessel equipped withelectrodes. A DC voltage (10 V) was applied to the vessel, and the DCcurrent was measured after 10 seconds. The specific resistance wascalculated from the following equation: (specificresistance)=[(voltage)×(electric capacity of vessel)]/[(DCcurrent)×(dielectric constant in vacuum)].

(15) Helical Pitch (P; Measured at Room Temperature; Micrometer):

The helical pitch was measured according to the wedge method (see page196 of “Ekishou Binran” (Liquid Crystal Handbook, in English; Maruzen,Co., LTD., Japan, 2000). After a sample had been injected into awedge-shaped cell and the cell had been allowed to stand at roomtemperature for 2 hours, the distance (d2−d1) between disclination lineswas observed with a polarizing microscope (Nikon Corporation, ModelMM-40/60 series). The helical pitch (P) was calculated from thefollowing equation, wherein θ was defined as the angle of the wedgecell: P=2×(d2−d1)×tan θ.

(16) Dielectric constant in the minor axis direction (∈⊥; measured at25° C.):

A sample was poured into a TN device in which the distance between thetwo glass substrates (cell gap) was 9 micrometers and the twist anglewas 80 degrees. Sine waves (0.5 V, 1 kHz) were applied to this deviceand the dielectric constant (∈⊥) in the minor axis direction of theliquid crystal molecules was measured after 2 seconds.

(17) Flicker Rate (Measured at 25° C.; %):

A multimedia display tester 3298F made by Yokogawa Electric Corporationwas used for measurement. The light source was LED. A sample was pouredinto a FFS device assembled in Examples described below. This device wassealed with a UV-curable adhesive. A voltage was applied to the deviceand a voltage was measured when the amount of light passed through thedevice reached a maximum. The sensor was approximated to the devicewhile this voltage was applied to the device, and the flicker ratedisplayed was recorded. The flicker rate is preferably 2% or less, andmore preferably 1% or less.

(18) Weight Average Molecular Weight (Mw):

The weight average molecular weight of a polyamic acid was measured by aGPC method using 2695 separation module 2414 differential refractometermade by Waters Corporation, and was expressed in terms of polystyreneequivalents. The resulting polyamic acid was diluted with a phosphoricacid-DMF mixed solution (phosphoric acid/DMF=0.6/100, in a weightratio), giving about approximately 2% by weight concentration of thepolyamic acid. A column used was HSPgel RT MB-M made by WatersCorporation, and the measurement was carried out under the conditions of50° C. of the column temperature and 0.40 mL/min of the current velocityusing the mixed solvent as an eluent A TSK standard polystyrene made byTosoh Corporation was used as the standard polystyrene.

(19) Pretilt Angle:

A spectroscopic ellipsometer M-2000U made by J. A. Woollam Co. Inc. wasused for the measurement of pretilt angles.

(20) AC Ghost Images (Brightness Change):

In the liquid crystal display device that will be described below, thebrightness-voltage characteristics (B-V characteristics) were measured.This was referred to as brightness-voltage characteristics beforestressed [B (before)]. Next, direct current 4.5 V, 60 Hz) was appliedfor 20 minutes to the device, and no voltages for 1 second, and then thebrightness-voltage characteristics (B-V characteristics) were measuredagain. This was referred to as brightness-voltage characteristics afterstressed [B (after)]. The brightness change (ΔB; %) was calculated fromthese values by the following equation:ΔB(%)=[B(after)−B(before)]/B(before)  (equation 1)These measurements were carried out by referring WO 2000-43833 A. Thesmaller value of ΔB (%) at a voltage of 0.75 V means a smallergeneration of AC ghost images.(21) Orientational Stability (Stability of Liquid Crystal OrientationalAxis):

In the liquid crystal display device that will be described below, thechange of a liquid crystal orientational axis in a side of electrode wasevaluated. A liquid crystal orientation angle [φ(before)] beforestressed in the side of an electrode was measured, and rectangular waves(4.5 V, 60 Hz) were applied for 20 minutes to the device, and the devicewas short-circuited for 1 second, and then the liquid crystalorientation angle [φ(after)] in the side of the electrode was measuredafter 1 second and 5 minutes. The change (Δφ, deg.) of the liquidcrystal orientation angle after 1 second and 5 minutes was calculatedfrom these values by the following equation:Δφ(deg.)=φ(after)−φ(before)  (equation 2)The measurement was performed by reference to J. Hilfiker, B. Johs, C.Herzinger, J. F. Elman, E. Montbach, D. Bryant, and P. J. Bos, ThinSolid Films, 455-456, (2004) 596-600. The smaller value of Δφ means thatthe change ratio of the liquid crystal orientational axis is smaller,and the stability of liquid crystal orientational axis is better.(22) Volume resistivity (p; measured at 25° C.; Ω·cm):

A polyimide film was formed on a glass substrate covered with ITOentirely. Aluminum was deposited to the side of the alignment film onthe substrate, which was referred to as an upper electrode (electrodesurface area: 0.23 cm²). A voltage of 3 V was applied between the ITOelectrode and the upper electrode, and the volume resistivity wascalculated from a current value after 300 seconds.

(23) Permittivity (∈; measured at 25° C.):

A polyimide film was prepared on a substrate covered with ITO entirely.Aluminum was deposited to the side of the alignment film on thesubstrate, which was referred to as an upper electrode (electrodesurface area: 0.23 cm²). An AC voltage (1 V, frequency 1 kHz) wasapplied between the ITO electrode and the upper electrode, and theelectric capacity (C) of the film was measured. The permittivity (8) ofthe film was calculated from this value by the following equation.∈=(C×d)/(∈₀ ×S)  (equation 3)where d is the film thickness of the polyimide film, ∈₀ is permittivityin vacuum, and S is the electrode surface area.(24) Abbreviations:

Abbreviations of solvents and additives used in Examples are as follows.

Solvent

NMP: N-Methyl-2-pyrrolidone.

BC: Butyl cellosolve (ethylene glycol monobutyl ether).

Additive

Additive (Ad1):Bis[4-(allylbicyclo[2.2.1]hept-5-ene-2,3-dicarboximide)phenyl]methane.

Additive (Ad2): N,N,N′,N′-Tetraglycidyl-4,4′-diaminodiphenylmethane.

Additive (Ad3): 3-Aminopropyltriethoxysilane.

Additive (Ad4): 2-(3,4-Epoxycyclohexyl)ethyltrimethoxysilane.

The compounds described in Examples were expressed in terms of symbolsaccording to the definition in Table 3 described below. In Table 3, theconfiguration of 1,4-cyclohexylene is trans. The parenthesized numbernext to a symbolized compound in Example corresponds to the number ofthe compound. The symbol (-) means any other liquid crystal compound.The ratio (percentage) of a liquid crystal compound is expressed as apercentage by weight (% by weight) based on the weight of the liquidcrystal composition. Last, the values of characteristics of thecomposition are summarized.

TABLE 3 Method of Description of Compounds using Symbols R—(A₁)—Z₁— . .. —Z n—(A_(n))—R′ Symbol 1) Left-terminal Group R— C_(n)H_(2n+1) n-C_(n)H_(2n+1)O— nO— C_(m)H_(2m+1)OC_(n)H_(2n)— mOn— CH₂═CH— V—C_(n)H_(2n+1)—CH═CH— nV— CH₂═CH—C_(n)H_(2n)— Vn—C_(m)H_(2m+1)—CH═CH—C_(n)H_(2n)— mVn— CF₂═CH— VFF— CF₂—CH—C_(n)H_(2n)—VFFn— F—C_(n)H_(2n)— Fn— 2) Right-terminal Group —R′ —C_(n)H_(2n+1) -n—OC_(n)H_(2n+1) —On —CH═CH₂ —V —CH═CH—C_(n)H_(2n+1) —Vn—C_(n)H_(2n)—CH═CH₂ —nV —C_(n)H_(2n)—CH═CH—C_(m)H_(2m+1) —nVm —CH═CF₂—VFF —COOCH₃ —EMe —F —F —Cl —CL —OCF₃ —OCF3 —CF₃ —CF3 —CN —C 3) BondingGroup —Z_(n)— —C₂H₄— 2 —COO— E —CH═CH— V —C≡C— T —CF₂O— X —CH₂O— 1O 4)Ring —A_(n)—

H

Dh

dh

B

B(F)

B(2F)

B(F,F)

B(2F,5F)

G

Py

B(2F,3F) 5) Examples of Description Example 1. V-HHB-1

Example 2. 3-BB(F)B(F,F)-F

Example 3. 4-BB(F)B(F,F)XB(F,F)-F

Example 4. 5-GB(F,F)XB(F,F)-F

Composition Example M1

3-HHXB(F,F)-F (1-4) 13%  3-BBXB(F,F)-F (1-17) 4% 3-BB(F,F)XB(F,F)-F(1-18) 10%  3-HBBXB(F,F)-F (1-23) 6% 3-HBB(F,F)XB(F,F)-F (1-24) 6%3-GB(F)B(F,F)XB(F,F)-F (1-27) 3% 4-GB(F)B(F,F)XB(F,F)-F (1-27) 3% 3-HH-V(2-1) 32%  3-HH-V1 (2-1) 7% V-HHB-1 (2-5) 6% V2-HHB-1 (2-5) 6%1-BB(F)B-2V (2-7) 4% NI = 84.5° C.; Tc < −30° C.; Δn = 0.101; Δε = 7.6;Vth = 1.56 V; η = 12.1 mPa · s; VHR-1 = 99.1%; VHR-2 = 98.2%; VHR-3 =98.1%.

Composition Example M2

3-HHXB(F,F)-CF3 (1-5) 4% 3-GB(F,F)XB(F,F)-F (1-14) 5% 3-BB(F)B(F,F)-F(1-15) 9% 3-BB(F,F)XB(F,F)-F (1-18) 17%  3-HBBXB(F,F)-F (1-23) 7%3-GB(F)B(F,F)XB(F,F)-F (1-27) 2% 3-BB(F)B(F,F)XB(F,F)-F (1-29) 2%4-BB(F)B(F,F)XB(F,F)-F (1-29) 6% 5-BB(F)B(F,F)XB(F,F)-F (1-29) 6% 3-HH-V(2-1) 21%  V-HHB-1 (2-5) 9% V2-HHB-1 (2-5) 9% 1-BB(F)B-2V (2-7) 3% NI =79.5° C.; Tc < −30° C.; Δn = 0.129; Δε = 15.9; Vth = 1.25 V; η = 21.2mPa · s.

Composition Example M3

3-HB(F)B(F,F)-F (1-9) 5% 3-GB(F)B(F,F)-F (1-12) 6% 3-BB(F,F)XB(F,F)-F(1-18) 2% 4-GB(F)B(F,F)XB(F,F)-F (1-27) 3% 4-BB(F)B(F,F)XB(F,F)-F (1-29)6% 3-HH-V (2-1) 31%  3-HH-V1 (2-1) 6% 1-HH-2V1 (2-1) 6% V-HHB-1 (2-5)14%  V2-HHB-1 (2-5) 12%  3-HHB-1 (2-5) 3% 3-HHB-O1 (2-5) 3% 2-BB(F)B-3(2-7) 3% NI = 92.1° C.; Tc < −20° C.; Δn = 0.095; Δε = 4.1; Vth = 2.05V; η = 13.3 mPa · s.

Composition Example M4

3-GB(F,F)XB(F)-F (1-13) 4% 3-BB(F,F)XB(F,F)-F (1-18) 18% 3-GB(F)B(F,F)XB(F,F)-F (1-27) 5% 4-GB(F)B(F,F)XB(F,F)-F (1-27) 3%5-GB(F)B(F,F)XB(F,F)-F (1-27) 3% 3-BB(F,F)XB(F)B(F,F)-F (1-30) 5% 3-HH-V(2-1) 24%  3-HH-V1 (2-1) 8% V-HHB-1 (2-5) 10%  V2-HHB-1 (2-5) 10% 3-HHB-1 (2-5) 4% 3-HBB-2 (2-6) 6% NI = 81.8° C.; Tc < −20° C.; Δn =0.105; Δε = 9.2; Vth = 1.46 V; η = 15.6 mPa · s.

Composition Example M5

3-HHB(F,F)-F (1-2) 5% 3-GHB(F,F)-F (1-7) 10%  3-HBB(F,F)-F (1-8) 10% 3-HHBB(F,F)-F (1-19) 6% 3-HBB(F,F)XB(F,F)-F (1-24) 4%4-GB(F)B(F,F)XB(F)-F (1-26) 3% 4-GB(F)B(F,F)XB(F,F)-F (1-27) 3% 3-HH-V(2-1) 34%  3-HH-V1 (2-1) 7% V-HHB-1 (2-5) 7% 3-BB(F)B-5 (2-7) 2%3-HHEBH-3 (2-10) 5% 5-HBB(F)B-2 (2-13) 4% NI = 97.9° C.; Tc < −20° C.;Δn = 0.100; Δε= 6.8; Vth = 1.80 V; η = 21.5 mPa · s.

Composition Example M6

3-HHEB(F,F)-F (1-3) 3% 3-GB(F)B(F,F)-F (1-12) 10% 4-GB(F)B(F,F)XB(F,F)-F (1-27) 3% 4-BB(F)B(F,F)XB(F,F)-F (1-29) 6%3-B(2F,3F)BXB(F,F)-F (1-33) 3% 3-HB(2F,3F)BXB(F,F)-F (1-34) 3% 3-HHB-F(1) 5% 3-HH-V1 (2-1) 6% 5-HH-V (2-1) 14%  3-HH-2V1 (2-1) 6% 3-HH-4 (2-1)11%  7-HB-1 (2-2) 3% 5-HB-O2 (2-2) 5% 3-HHEH-3 (2-4) 3% V-HHB-1 (2-5) 6%V2-HHB-1 (2-5) 9% 2-BB(F)B-3 (2-7) 4% NI = 90.0° C.; Tc < −30° C.; Δn =0.098; Δε = 6.0; Vth = 1.89 V; η = 18.6 mPa · s.

Composition Example M7

3-GB(F,F)XB(F,F)-F (1-14) 8% 3-BB(F,F)XB(F,F)-F (1-18) 5% 3-HBBXB(F,F)-F(1-23) 6% 3-HBB(F,F)XB(F,F)-F (1-24) 7% 3-BB(F,F)XB(F)-OCF3 (1) 5%3-HH-V (2-1) 12%  4-HH-V (2-1) 8% F3-HH-V (2-1) 11%  V-HHB-1 (2-5) 7%3-HHB-3 (2-5) 4% V-HBB-2 (2-6) 7% V2-BB(F)B-1 (2-7) 3% 2-BB(2F,3F)B-3(3-9) 12%  3-HBB(2F,3F)-O2 (3-13) 5% NI = 84.9° C.; Tc < −30° C.; Δn =0.125; Δε = 5.6; Vth = 1.82 V; η = 13.8 mPa · s.

Composition Example M8

3-HHXB(F,F)-F (1-4) 9% 3-BB(F,F)XB(F,F)-F (1-18) 16% 3-dhBB(F,F)XB(F,F)-F (1-25) 8% 3-BB(F)B(F,F)XB(F,F)-F (1-29) 5% 3-HH-V(2-1) 22%  3-HH-V1 (2-1) 10%  1-BB-5 (2-3) 8% 3-HHB-O1 (2-5) 5% 3-HBB-2(2-6) 5% 1V-HBB-2 (2-6) 5% 3-HB(F)BH-3 (2-12) 4% 5-HB(F)BH-3 (2-12) 3%NI = 70.0° C.; Tc < −20° C.; Δn = 0.096; Δε = 7.3; Vth = 1.52 V; η =11.4 mPa · s.

Composition Example M9

3-BB(F)B(F,F)-F (1-15) 6% 3-BB(F)B(F,F)-CF3 (1-16) 3% 3-BB(F,F)XB(F,F)-F(1-18) 4% 3-HBBXB(F,F)-F (1-23) 5% 4-GB(F)B(F,F)XB(F,F)-F (1-27) 4%4-BB(F)B(F,F)XB(F,F)-F (1-29) 7% 3-BB(2F,3F)BXB(F,F)-F (1-35) 2% 3-HH-V(2-1) 30%  3-HH-V1 (2-1) 6% 3-HH-VFF (2-1) 8% 3-HB-O2 (2-2) 3% V-HHB-1(2-5) 5% 1-BB(F)B-2V (2-7) 4% 2-BB(F)B-2V (2-7) 4% 3-HB(2F,3F)-O2 (3-1)3% 3-BB(2F,3F)-O2 (3-4) 3% 3-HHB(2F,3F)-O2 (3-6) 3% NI = 75.2° C.; Tc <−20° C.; Δn = 0.111; Δε = 5.4; Vth = 1.85 V; η = 12.2 mPa · s.

Composition Example M10

3-HGB(F,F)-F (1-6) 6% 4-GB(F)B(F,F)XB(F,F)-F (1-27) 3%3-BB(F)B(F,F)XB(F,F)-F (1-29) 2% 4-BB(F)B(F,F)XB(F,F)-F (1-29) 5%5-BB(F)B(F,F)XB(F,F)-F (1-29) 6% 3-HHB-CL (1) 3% 3-HH-V (2-1) 30% 2-HH-3 (2-1) 7% V-HHB-1 (2-5) 15%  V2-HHB-1 (2-5) 8% 3-HHEBH-4 (2-10) 3%5-HBB(F)B-2 (2-13) 7% 5-HBB(F)B-3 (2-13) 5% NI = 117.6° C.; Tc < −30°C.; Δn = 0.115; Δε = 4.2; Vth = 2.45 V; η = 14.5 mPa · s.

Composition Example M11

3-BB(F)B(F,F)-F (1-15) 21%  2O-B(2F,3F)BXB(F,F)-F (1-33) 4% 3-HB-CL (1)5% 3-HH-V (2-1) 25%  4-HH-V1 (2-1) 3% V2-BB-1 (2-3) 5% 1V2-BB-1 (2-3) 5%1-BB(F)B-2V (2-7) 8% 2-BB(F)B-2V (2-7) 8% 3-BB(F)B-2V (2-7) 8%5-B(F)BB-2 (2-8) 4% 5-HBBH-1O1 (—) 4% NI = 78.2° C.; Tc < −10° C.; Δn =0.166; Δε = 3.8; Vth = 2.47 V; η = 25.5 mPa · s.

Composition Example M12

3-HHXB(F,F)-F (1-4) 2% 3-GB(F)B(F)-F (1-11) 8% 3-GB(F)B(F)B(F)-F (1-21)2% 4-GBB(F)B(F,F)-F (1-22) 3% 3-BB(2F,3F)XB(F,F)-F (1-32) 9% 3-HHB(F)-F(1) 3% 3-HBB(F)-F (1) 3% 3-HH-V (2-1) 30%  F3-HH-V (2-1) 8% 3-HB-O2(2-2) 5% V-HBB-2 (2-6) 6% 1-BB(F)B-2V (2-7) 4% 2-BB(F)B-2V (2-7) 6%3-BB(F)B-2V (2-7) 5% 5-HBBH-3 (2-11) 3% 3-dhBB(2F,3F)-O2 (3-14) 3% NI =82.2° C.; Tc < −30° C.; Δn = 0.124; Δε = 3.1; Vth = 2.41 V; η = 16.4 mPa· s.

Composition Example M13

5-HXB(F,F)-F (1-1) 3% 3-BB(F)B(F,F)XB(F)-F (1-28) 5%4-BB(F)B(F,F)XB(F,F)-F (1-29) 4% 3-BB(F)B(F,F)XB(F)B(F,F)-F (1-31) 3%3-HHXB(F,F)-OCF3 (1) 7% 3-HH2B(F,F)-F (1) 4% 3-HH-V (2-1) 44%  3-HH-V1(2-1) 5% V-HHB-1 (2-5) 7% V2-HHB-1 (2-5) 5% 3-HHB-1 (2-5) 3% 2-BB(F)B-2V(2-7) 3% 3-BB(F)B-2V (2-7) 3% 3-HB(F)HH-5 (2-9) 4% NI = 100.6° C.; Tc <−20° C.; Δn = 0.101; Δε = 3.6; Vth = 2.35 V; η = 10.2 mPa · s.

Composition Example M14

3-HBEB(F,F)-F (1-10) 5% 3-HBBXB(F,F)-F (1-23) 10% 3-BB(F)B(F,F)XB(F,F)-F (1-29) 2% 4-BB(F)B(F,F)XB(F,F)-F (1-29) 7%3-HBB-F (1) 3% 3-dhB(F,F)XB(F,F)-F (1) 8% 3-HH-V (2-1) 35%  1-HH-2V1(2-1) 5% 3-HH-2V1 (2-1) 4% 3-HH-O1 (2-1) 5% V-HHB-1 (2-5) 8% 3-HHB-1(2-5) 4% 3-HB(F)BH-3 (2-12) 4% NI = 85.6° C.; Tc < −30° C.; Δn = 0.096;Δε = 5.5; Vth = 1.75 V; η = 13.7 mPa · s.

1. Preparation of polyamic acid solutions (component A Synthetic Example1

In a brown four-neck flask 50 mL equipped with a thermometer, a stirrer,an inlet for starting materials and a nitrogen gas inlet, 1.7806 g ofdiamine (DI-5-12, m=5) and 18.5 g of dry NMP were placed, and stirred todissolve under a stream of dry nitrogen. Then, 1.2194 g oftetracarboxylic acid dianhydride (XI-1-1) and 18.5 g of dry NMP wereadded, and the mixture was stirred at room temperature for 24 hours.10.0 g of BC was added to this reaction mixture to give a polyamic acidsolution with a polymer solid content of 6% by weight. The polyamic acidsolution was referred to as PAA1. The weight-average molecular weight ofthe polyamic acid included in PAA1 was 38,000.

Synthetic Examples 2 to 16

Polyamic acid solutions (PAA2) to (PAA16) with a polymer solid contentof 6% by weight were prepared according to Synthetic Example 1 exceptthat the type of tetracarboxylic acid dianhydrides and diamines werechanged. Polyamic acid solutions (PAA1) to (PAA16) were referred to ascomponent A. Table 4 summarizes the results.

TABLE 4 Preparation pf polyamic acids (PAA1) to (PAA16) Syn- Startingmaterials of the Polyamic acids thetic Poly- Tetracarboxylic WeightExam- amic acid average ples acids dianhydrides Diamines molecular No..No. (mol %) (mol %) weight 1 PAA1 XI-1-1 (100) DI-5-12 (m = 5) (100)38,000 2 PAA2 XI-1-1 (100) DI-5-12 (m = 5) (50) 42,000 DI-4-1 (50) 3PAA3 XI-1-2 (100) DI-5-12 (m = 5) (100) 41,500 4 PAA4 XI-1-2 (100)DI-5-12 (m = 5) (50) 35,250 DI-4-1 (50) 5 PAA5 XI-1-3 (100) DI-5-12 (m =5) (100) 45,650 6 PAA6 XI-1-3 (100) DI-5-12 (m = 5) (50) 40,420 DI-4-1(50) 7 PAA7 XI-1-5 (100) DI-5-12 (m = 5) (100) 41,100 8 PAA8 XI-1-5(100) DI-5-12 (m = 5) (50) 37,800 DI-4-1 (50) 9 PAA9 XI-1-1 (100)DI-5-12 (m = 5) (80) 45,200 DI-4-d (20) 10 PAA10 XI-1-5 (100) DI-5-12 (m= 5) (80) 38,500 DI-4-d (20) 11 PAA11 XI-1-1 (100) DI-4-1 (80) 42,000DI-4-d (20) 12 PAA12 XI-1-5 (100) DI-4-1 (80) 35,900 DI-4-d (20) 13PAA13 XI-1-1 (100) DI-5-28 (100) 45,000 14 PAA14 XI-12 (100) DI-5-28(100) 47,250 15 PAA15 AN-1-1 (100) DI-5-28 (100) 44,000 16 PAA16 XI-1-1(100) DI-5-12 (m = 2) (100) 41,200

2. Preparation of polyamic acid ester solutions (component B SyntheticExample 17

In a brown four-neck flask 50 mL equipped with a thermometer, a stirrer,an inlet for starting materials and a nitrogen gas inlet, 1.4725 g ofdiamine (DI-5-12, m=5), 18.5 g of dry NMP and 0.407 g of pyridine as abase were placed, and stirred to dissolve under a stream of drynitrogen. Then, 1.5275 g of dimethyl1,3-bis(chlorocarbonyl)-1,3-dimethylcyclobutane-2,4-dicarboxylate and18.5 g of dry NMP were added, and the mixture was stirred underwater-cooling for 6 hours. The pyridine was removed by distillation, and10.0 g of NMP was added to this reaction mixture to give a polyamic acidester solution with a polymer solid content of 6% by weight. Thepolyamic acid ester solution was referred to as PAE1. The weight-averagemolecular weight of the polyamic acid ester included in PAE1 was 11,000.

Synthetic Examples 18 to 27

Polyamic acid ester solutions (PAE2) to (PAE11) with a polymer solidcontent of 6% by weight were prepared according to Synthetic Example 17except that the type of tetracarboxylic acid diester dichlorides anddiamines were changed. Polyamic acid ester solutions (PAE2) to (PAE11)were referred to as component B. Table 5 summarizes the results.

TABLE 5 Preparation of polyamic acid esters (PAE1) to (PAE11) Syn- Poly-Starting materials of the Polyamic acid esters thetic amicTetracarboxylic Weight Exam- acid acid diester average ples estersdichlorides¹⁾ ²⁾ Diamines molecular No. No. (mol %) (mol %) weight 17PAE1 Compound (d-2) (100) DI-5-12 (m = 5) (100) 11,000 18 PAE2 Compound(d-2) (100) DI-5-12 (m = 5) (50) 11,250 DI-4-1 (50) 19 PAE3 Compound(d-2) (100) DI-4-1 (100) 12,050 20 PAE4 Compound (d-1) (100) DI-5-12 (m= 5) (100) 10,200 21 PAE5 Compound (d-1) (100) DI-5-12 (m = 5) (50)9,800 DI-4-1 (50) 22 PAE6 Compound (d-1) (100) DI-4-1 (100) 10,500 23PAE7 Compound (d-2) (100) DI-4-10 (50) 10,700 DI-4-1 (50) 24 PAE8Compound (d-2) (100) DI-5-12 (m = 2) (100) 11,050 25 PAE9 Compound (d-2)(100) DI-5-12 (m = 5) (70) 12,040 DI-4-1 (30) 26 PAE10 Compound (d-1)(100) DI-5-12 (m = 2) (100) 10,030 27 PAE11 Compound (d-1) (100) DI-5-12(m = 2) (70) 9,900 DI-4-1 (30) ¹⁾Compound (d-1): Dimethyl1,3-bis(chlorocarbonyl)cyclobutan-2,4-dicarboxylate ²⁾Compound (d-2):Dimethyl1,3-bis(chlorocarbonyl)-1,3-dimethylcyclobutan-2,4-dicarboxylate

Example 1

Formation of an Alignment Film from the Polyamic Acid

A mixed solvent of NMP/BC=4/1 (ratio by weight) was added to polyamicacid solution (PAA1) with a polymer solid content of 6% by weightprepared in Synthetic Example 1 to give the liquid crystal aligningagent with a polymer solid content of 4% by weight. The liquid crystalaligning agent was applied to a glass substrate with a column spacer anda glass substrate with an ITO electrode, with a spinner (a spin coater1H-DX2 made by Mikasa Co., Ltd). Incidentally, the film thicknessdescribed below was adjusted by changing the rotating rate of thespinner according to the viscosity of liquid crystal aligning agents,which was applied to the following Examples and Comparative Examples.The coating film was heated and dried at 70° C. for 80 seconds on ahot-plate (an EC hot-plate EC-1200N made by As One Corporation). Then,the coating film was heated at 230° C. for 20 minutes in a clean oven (aclean oven PVHC-231 made by Espec Corporation) to form an alignment filmwith film thickness of 100±10 nm. The film on the substrate wasvertically irradiated with linearly polarized ultraviolet light via apolarizing plate using Multilight ML-501C/B made by Ushio, Inc. Theamount of light was measured with an accumulated UV meter UIT-150(receiver UVD-5365) made by Ushio, Inc. and the exposure energy wasadjusted to be 0.5±0.1 J/cm² at a wavelength of 254 nm by changing theexposure time. After irradiation, the substrate was immersed in ethyllactate for 3 minutes, and in hyperpure water for 1 minute, and dried at200° C. for 10 minutes in the clean oven.

Production of Devices

An FFS device was assembled in which two substrates were pastedtogether, the surfaces of the alignment films were inside, and thedirections of linearly polarized ultraviolet light were parallel, andthe distance between the substrates was 4 micrometers. An injectioninlet for liquid crystals was located at a position where the flowdirection of liquid crystals was roughly parallel to the linearlypolarized ultraviolet light. The liquid crystal composition inComposition Example M1 was injected to this FFS device, and the responsetime and the flicker rate were measured. Table 6 summarizes the results.Incidentally, the liquid crystal composition in Composition Example M1is abbreviated to “Composition M1”. The same rule applies to otherliquid crystal compositions.

Examples 2 to 13

A mixed solvent of NMP/BC=4/1 (ratio by weight) was added to each ofpolyamic acid solutions (PAA2) to (PAA12), prepared in SyntheticExamples 2 to 12 and Synthetic Example 16, with a polymer solid contentof 6% by weight to give a liquid crystal aligning agent with a polymersolid content of 4% by weight. The device was produced in a similarmanner, and the response time and the flicker rate were measured. Table6 summarizes the results.

TABLE 6 Response time and Flicker rate (Part 1) Polyamic CharacteristicsExamples acids Compositions Response time Flicker rate No. No. No. (ms)(%) 1 PAA1 M1 20.2 0.41 2 PAA2 M2 35.3 0.42 3 PAA3 M3 21.7 0.26 4 PAA4M4 26.1 0.04 5 PAA5 M5 35.2 0.69 6 PAA6 M6 30.9 0.30 7 PAA7 M8 19.3 0.328 PAA8 M9 20.1 0.33 9 PAA9 M10 24.1 0.16 10 PAA10 M11 42.1 0.14 11 PAA11M12 26.8 0.21 12 PAA12 M13 17.0 0.57 13 PAA16 M14 22.9 0.24

Example 14

Formation of Alignment Films from the Polyamic Acid and the PolyamicAcid Ester

Polyamic acid solution (PAA13) with a polymer solid content of 6% byweight, which is prepared in Synthetic Example 13, and polyamic acidester solution (PAE1) with a polymer solid content of 6% by weight,which is prepared in Synthetic Example 17, were mixed in the ratio of 7to 3. A mixed solvent of NMP/BC=4/1 (weight ratio) was added to themixture to give a liquid crystal aligning agent with a polymer solidcontent of 4% by weight. The liquid crystal aligning agent was appliedto a glass substrate with a column spacer and a glass substrate with anITO electrode, with a spinner (a spin coater 1H-DX2 made by Mikasa Co.,Ltd). Incidentally, the film thickness described below was adjusted bychanging the rotating rate of the spinner according to the viscosity ofliquid crystal aligning agents, which was applied to the followingExamples and Comparative Examples. The coating film was heated and driedat 70° C. for 80 seconds on a hot-plate (an EC hot-plate EC-1200N madeby As One Corporation). Then, the coating film was heated at 230° C. for20 minutes in a clean oven (a clean oven PVHC-231 made by EspecCorporation) to form an alignment film with film thickness of 100±10 nm.The substrate was vertically irradiated with linearly polarizedultraviolet light via a polarizing plate using Multilight ML-501C/B madeby Ushio, Inc. The amount of light was measured with an accumulated UVmeter UIT-150 (receiver UVD-S365) made by Ushio, Inc. and the exposureenergy was adjusted to be 0.5±0.1 J/cm² at a wavelength of 254 nm bychanging the exposure time. After irradiation, the substrate wasimmersed in ethyl lactate for 3 minutes, and in hyperpure water for 1minute, and dried at 200° C. for 10 minutes in the clean oven.

Production of Devices

An FFS device was assembled in which two substrates were pastedtogether, the surfaces of the alignment films were inside, and thedirections of linearly polarized ultraviolet light were parallel, andthe distance between the substrates was 4 micrometers. An injectioninlet for liquid crystals was located at a position where the flowdirection of liquid crystals was roughly parallel to the linearlypolarized ultraviolet light. The liquid crystal composition inComposition Example M1 was injected to this FFS device, and the responsetime and the flicker rate were measured. Table 7 summarizes the results.Incidentally, the liquid crystal composition in Composition Example M1is abbreviated to “Composition M1”. The same rule applies to otherliquid crystal compositions.

Examples 15 to 49

Component A was mixed with component B in a manner similar to that inExample 14, and a device was produced in a similar manner. The responsetime and the flicker rate were measured. Table 7 summarizes the results.

TABLE 7 Response time and Flicker rate (Part 2) Starting materials ofAligning the Aligning agents Characteristics Examples agents Component AComponent B Compositions Response Flicker rate No. No. (% by weight) (%by weight) No. time (ms) (%) 14 PA1 PAA13 (70) PAE1 (30) M1 20.1 0.34 15PA2 PAA13 (70) PAE2 (30) M2 34.9 0.33 16 PA3 PAA13 (70) PAE3 (30) M321.5 0.20 17 PA4 PAA13 (70) PAE4 (30) M4 25.4 0.02 18 PA5 PAA13 (70)PAE5 (30) M5 34.8 0.56 19 PA6 PAA13 (70) PAE6 (30) M6 31.1 0.24 20 PA7PAA13 (70) PAE7 (30) M9 20.5 0.25 21 PA8 PAA13 (70) PAE8 (30) M10 24.40.13 22 PA9 PAA13 (70) PAE9 (30) M11 42.2 0.12 23 PA10 PAA13 (70) PAE10(30) M13 16.8 0.46 24 PA11 PAA13 (70) PAE11 (30) M14 23.0 0.19 25 PA12PAA14 (70) PAE1 (30) M1 20.4 0.31 26 PA13 PAA14 (70) PAE2 (30) M2 35.40.29 27 PA14 PAA14 (70) PAE3 (30) M3 21.6 0.21 28 PA15 PAA14 (70) PAE4(30) M4 25.2 0.03 29 PA16 PAA14 (70) PAE5 (30) M5 34.6 0.57 30 PA17PAA14 (70) PAE6 (30) M6 30.9 0.21 31 PA18 PAA14 (70) PAE7 (30) M9 20.70.24 32 PA19 PAA14 (70) PAE8 (30) M10 24.8 0.14 33 PA20 PAA14 (70) PAE9(30) M11 41.9 0.11 34 PA21 PAA14 (70) PAE10 (30) M13 17.2 0.45 35 PA22PAA14 (70) PAE11 (30) M14 23.3 0.20 36 PA23 PAA15 (70) PAE1 (30) M1 19.90.34 37 PA24 PAA15 (70) PAE2 (30) M2 35.1 0.36 38 PA25 PAA15 (70) PAE3(30) M3 21.3 0.21 39 PA26 PAA15 (70) PAE4 (30) M4 25.7 0.04 40 PA27PAA15 (70) PAE5 (30) M5 34.5 0.59 41 PA28 PAA15 (70) PAE6 (30) M6 31.70.26 42 PA29 PAA15 (70) PAE7 (30) M9 20.1 0.23 43 PA30 PAA15 (70) PAE8(30) M10 24.6 0.15 44 PA31 PAA15 (70) PAE9 (30) M11 41.8 0.10 45 PA32PAA15 (70) PAE10 (30) M13 17.2 0.49 46 PA33 PAA15 (70) PAE11 (30) M1423.0 0.22 47 PA34 PAA13 (80) PAE8 (20) M7 22.9 0.61 48 PA35 PAA14 (80)PAE8 (20) M8 18.7 0.27 49 PA36 PAA15 (80) PAE8 (20) M12 26.9 0.18

In the third column of Table 6 and the fifth column of Table 7, the typeof compositions injected to the FFS devices is described. These are theliquid crystal compositions prepared in Composition Example M1 toComposition Example M14. In these compositions, the maximum temperature(NI) is in the range of 70.0° C. to 117.6° C. The minimum temperature(Tc) is in the range of <−10° C. to <−30° C. The optical anisotropy (Δn)is in the range of 0.095 to 0.129. The dielectric anisotropy (Δ∈) is inthe range of 3.1 to 15.9. The viscosity (η) is in the range of 10.2mPa·s to 25.5 mPa·s. Fourteen liquid crystal compositions with differenttypes of characteristics were injected to a liquid crystal displaydevice with different types of alignment films, and then the responsetime and flicker rate of the device were measured.

In a liquid crystal display device, a shorter response time isdesirable. The response time is preferably 60 ms or less, and morepreferably 40 ms or less. A smaller flicker rate is desirable. Theflicker rate is preferably 2% or less, and more preferably 1% or less.The response time in Examples 1 to 49 was in the range of 16.8 ms to42.2 ms and the flicker rate was in the range of 0.02% to 0.69%. Thesevalues fell within the more desirable ranges. From these results, we nowconclude that the values of the response time and the flicker rate camewithin such a suitable range, although the types of components in theliquid crystal compositions and the alignment films were quitedifferent. This is the first feature of the invention that is worthy ofspecial mention. In the devices in Examples 5, 12, 18, 29, 40 and 47,the flicker rates were 0.5% or more. The response time of these deviceswere 35.2 ms, 17.0 ms, 34.8 ms, 34.6 ms, 34.5 ms and 22.9 ms,respectively. These findings shows that the flicker rate is small evenin the devices that have short response time. This is the second featureof the invention that is worthy of special mention.

INDUSTRIAL APPLICABILITY

The liquid crystal display device of the invention has characteristicssuch as a short response time, a large voltage holding ratio, a lowthreshold voltage, a large contrast ratio, a long service life and asmall flicker rate. The device thus can be used for a liquid crystalprojector, a liquid crystal television and so forth.

What is claimed is:
 1. A liquid crystal display device having anelectrode group formed on one or both of a pair of substrates that areopposed to each other, and a plurality of active devices connected tothe electrode group, and a liquid crystal alignment film formed on theopposing surfaces of the pair of substrates, and a liquid crystalcomposition sandwiched in between the pair of substrates, wherein theliquid crystal alignment film comprises a polymer derived from apolyamic acid having a photodegradable group and gains, byphotoirradiation that photodegrades the photodegradable group, abilityfor orientation of liquid crystals so that the polymer has a groupformed through the photodegradation of the photodegradable group, andthe liquid crystal composition comprises at least one compoundrepresented by formula (1) as a first component:

in formula (1), R¹ is alkyl having 1 to 12 carbons, alkoxy having 1 to12 carbons or alkenyl having 2 to 12 carbons; ring A is1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,2,3-difluoro-1,4-phenylene, 2,6-difluoro-1,4-phenylene,pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl or tetrahydropyran-2,5-diyl;Z¹ is a single bond, ethylene, carbonyloxy or difluoromethyleneoxy; X¹and X² are independently hydrogen or fluorine; Y¹ is fluorine, chlorine,alkyl having 1 to 12 carbons in which at least one hydrogen has beenreplaced by fluorine or chlorine, alkoxy having 1 to 12 carbons in whichat least one hydrogen has been replaced by fluorine or chlorine oralkenyloxy having 2 to 12 carbons in which at least one hydrogen hasbeen replaced by fluorine or chlorine; and a is 1, 2, 3 or 4, whereinthe photodegradable group is selected from the group of groupsrepresented by formula (XI-1) to formula (XI-16):

in formula (XI-1) to formula (XI-16), R⁶, R⁷, R⁸ and R⁹ areindependently hydrogen, halogen, alkyl having 1 to 6 carbons, alkenylhaving 2 to 6 carbons, alkynyl having 2 to 6 carbons or phenyl; R¹⁰ ishydrogen, alkyl having 1 to 10 carbons or cycloalkyl having 3 to 10carbons; n₁ is an integer from 1 to 4; when n₁ is 1, Z⁵ is —SCH₂—, andwhen n₁ is 2, 3 or 4, Z⁵ is a single bond, —SCH₂— or —CH₂S—, with theproviso that at least one of Z⁵ is —SCH₂— or —CH₂S—; and Z⁶ is a groupcomprising an aromatic ring.
 2. The liquid crystal display deviceaccording to claim 1, wherein the first component is at least onecompound selected from the group of compounds represented by formula(1-1) to formula (1-35):

in formula (1-1) to formula (1-35), R¹ is alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons.
 3. Theliquid crystal display device according to claim 1, wherein the ratio ofthe first component is in the range of 10% by weight to 90% by weightbased on the weight of the liquid crystal composition.
 4. The liquidcrystal display device according to claim 1, wherein the liquid crystalcomposition comprises at least one compound selected from the group ofcompounds represented by formula (2) as a second component:

in formula (2), R² and R³ are independently alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons,alkyl having 1 to 12 carbons in which at least one hydrogen has beenreplaced by fluorine or chlorine or alkenyl having 2 to 12 carbons inwhich at least one hydrogen has been replaced by fluorine or chlorine;ring B and ring C are independently 1,4-cyclohexylene, 1,4-phenylene,2-fluoro-1,4-phenylene or 2,5-difluoro-1,4-phenylene; Z² is a singlebond, ethylene or carbonyloxy; and b is 1, 2 or
 3. 5. The liquid crystaldisplay device according to claim 4, wherein the second component is atleast one compound selected from the group of compounds represented byformula (2-1) to formula (2-13):

in formula (2-1) to formula (2-13), R² and R³ are independently alkylhaving 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2to 12 carbons, alkyl having 1 to 12 carbons in which at least onehydrogen has been replaced by fluorine or chlorine or alkenyl having 2to 12 carbons in which at least one hydrogen has been replaced byfluorine or chlorine.
 6. The liquid crystal display device according toclaim 4, wherein the ratio of the second component is in the range of10% by weight to 90% by weight based on the weight of the liquid crystalcomposition.
 7. The liquid crystal display device according to claim 1,wherein the liquid crystal composition comprises at least one compoundselected from the group of compounds represented by formula (31 as athird component:

in formula (3), R⁴ and R⁵ are independently alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons,alkenyloxy having 2 to 12 carbons or alkyl having 1 to 12 carbons inwhich at least one hydrogen has been replaced by fluorine or chlorine;ring D and ring F are independently 1,4-cyclohexylene,1,4-cyclohexylene, 1,4-phenylene, 1,4-phenylene in which at least onehydrogen has been replaced by fluorine or chlorine ortetrahydropyran-2,5-diyl; ring E is 2,3-difluoro-1,4-phenylene,2-chloro-3-fluoro-1,4-phenylene, 2,3-difluoro-5-methyl-1,4-phenylene,3,4,5-trifluoronaphthalene-2,6-diyl or 7,8-difluorochroman-2,6-diyl; Z³and Z⁴ are independently a single bond, ethylene, carbonyloxy ormethyleneoxy; c is 1, 2 or 3, d is 0 or 1; and the sum of c and d is 3or less.
 8. The liquid crystal display device according to claim 7,wherein the third component is at least one compound selected from thegroup of compounds represented by formula (3-1) to formula (3-21):

in formula (3-1) to formula (3-21), R⁴ and R⁵ are independently alkylhaving 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2to 12 carbons, alkenyloxy having 2 to 12 carbons or alkyl having 1 to 12carbons in which at least one hydrogen has been replaced by fluorine orchlorine.
 9. The liquid crystal display device according to claim 7,wherein the ratio of the third component is in the range of 3% by weightto 30% by weight based on the weight of the liquid crystal composition.10. The liquid crystal display device according to claim 1, wherein theliquid crystal alignment film comprises a polymer derived by furtherusing at least one compound selected from the group of compoundsrepresented by formula (DI-1) to formula (DI-15):

in formula (DI-1) to formula (DI-7), k is an integer from 1 to 12; G²¹is a single bond, —NH—, —O—, —S—, —S—S—, —SO₂—, —CO—, —CONH—,—CON(CH₃)—, —NHCO—, —C(CH₃)₂ ⁻, —C(CF₃)₂ ⁻, —(CH₂)_(m)—, —O—(CH₂)—,—O—,—N(CH₃)—(CH₂)_(n)—N(CH₃)—,—COO—, —COS— or —S—(CH₂)_(m)—S—; m is aninteger from 1 to 12; n is an integer from 1 to 5; G²² is a single bond,—O—, —S—, —CO—, —C(CH₃)₂—, —C(CF₃)₂— or alkylene having 1 to 10 carbons;at least one hydrogen on the cyclohexane ring or the benzene ring may bereplaced by fluorine, —CH₃, —OH, —CF₃, —CO₂H, —CONH₂ or benzyl, and informula (DI-4), at least one hydrogen on the benzene ring may bereplaced by the following monovalent group represented by formula(DI-4-a) to formula (DI-4-d);

R¹¹ is hydrogen or —CH₃; and a group can be bonded to any one of carbonatoms constituting a ring when the bonding position of the group is notfixed to any one of the carbon atoms, and —NH₂ is bonded to any one ofthe bonding positions on a cyclohexane ring or a benzene ring excludingthe bonding position of G²¹ or G²²; and

in formula (DI-8) to formula (DI-12), R¹² and R¹³ are independentlyalkyl having 1 to 3 carbons or phenyl; G²³ is alkylene having 1 to 6carbons, phenylene or phenylene in which at least one hydrogen has beenreplaced by alkyl; p is an integer from 1 to 10; R¹⁴ is alkyl having 1to 5 carbons, alkoxy having 1 to 5 carbons or chlorine; q is an integerfrom 0 to 3; r is an integer from 0 to 4; R¹⁵ is hydrogen, alkyl having1 to 4 carbons, phenyl or benzyl; G²⁴ is —CH₂— or —NH—; G²⁵ is a singlebond, alkylene having 2 to 6 carbons or 1,4-phenylene; s is 0 or 1; agroup can be bonded to any one of carbon atoms constituting a ring whenthe bonding position of the group is not fixed to any one of the carbonatoms; and —NH₂ is bonded to any one of the bonding positions on abenzene ring; and

in formula (DI-13) to formula (DI-15), G³¹ is a single bond, alkylenehaving 1 to 20 carbons, —CO—, —O—, —S—, —SO₂—, —C(CH₃)₂— or —C(CF₃)₂—;ring K is a cyclohexane ring, a benzene ring or a naphthalene ring, andin these groups at least one hydrogen may be replaced by methyl, ethylor phenyl; and ring L is a cyclohexane ring or a benzene ring, and inthese groups at least one hydrogen may be replaced by methyl, ethyl orphenyl.
 11. The liquid crystal display device according to claim 1,wherein the liquid crystal alignment film comprises a polymer derived byfurther using a compound selected from the group of compoundsrepresented by formula (DI-1-3), formula (DI-4-1), formula (DI-5-1),formula (DI-5-5), formula (DI-5-9), formula (DI-5-12), formula(DI-5-22), formula (DI-5-28), formula (DI-5-30), formula (DI-5-31),formula (DI-7-3), formula (DI-9-1), formula (DI-13-1), formula(DI-13-2), formula (DI-14-1) and formula (DI-14-2):

in formula (DI-1-3), formula (DI-4-1), formula (DI-5-1), formula(DI-5-5), formula (DI-5-9), formula (DI-5-12), formula (DI-5-22),formula (DI-5-28), formula (DI-5-30), formula (DI-5-31), formula(DI-7-3), formula (DI-9-1), formula (DI-13-1), formula (DI-13-2),formula (DI-14-1) and formula (DI-14-2), m is an integer from 1 to 12; nis an integer from 1 to 5; and t is 1 or
 2. 12. The liquid crystaldisplay device according to claim 1, wherein the operating mode of theliquid crystal display device is a TN mode, an ECB mode, an OCB mode, anIPS mode, an FFS mode, a PSA mode, or an FPA mode, and the driving modeof the liquid crystal display device is an active matrix mode.
 13. Aliquid crystal composition used for the liquid crystal display deviceaccording to claim
 1. 14. The liquid crystal composition according toclaim 13, wherein at 25° C., the elastic constant (K) is 13 pN or moreand the ratio of the elastic constant (K) to the viscosity (n) is 0.8nN/Pa·s (nm²/s) or more.
 15. A liquid crystal display device, whereinthe device comprises the liquid crystal composition according to claim14, and the flicker rate at 25° C. is in the range of 0% to 1%.
 16. Aliquid crystal alignment film used for the liquid crystal display deviceaccording to claim
 1. 17. The liquid crystal alignment film according toclaim 16, wherein the volume resistivity (p) at 25° C. is 1.0×10¹⁴ Ωcmor more.
 18. The liquid crystal alignment film according to claim 16,wherein the dielectric constant (c) at 25° C. is in the range of 3 to 5.19. The liquid crystal display device according to claim 4, wherein theliquid crystal composition comprises at least one compound selected fromthe group of compounds represented by formula (3) as a third component:

in formula (3), R⁴ and R⁵ are independently alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons,alkenyloxy having 2 to 12 carbons or alkyl having 1 to 12 carbons inwhich at least one hydrogen has been replaced by fluorine or chlorine;ring D and ring F are independently 1,4-cyclohexylene,1,4-cyclohexylene, 1,4-phenylene, 1,4-phenylene in which at least onehydrogen has been replaced by fluorine or chlorine ortetrahydropyran-2,5-diyl; ring E is 2,3 -difluoro-1,4-phenylene,2-chloro-3-fluoro-1,4-phenylene, 2,3-difluoro-5-methyl-1,4-phenylene,3,4,5-trifluoronaphthalene-2,6-diyl or 7,8-difluorochroman-2,6-diyl; Z³and Z⁴ are independently a single bond, ethylene, carbonyloxy ormethyleneoxy; c is 1, 2 or 3, d is 0 or 1; and the sum of c and d is 3or less.